Document And Entity Information
Note To Financial Statement Details Textual
statementsignificantaccountingpoliciespolicies
statementnote2summaryofsignificantaccountingpoliciestables
statementnote3marketablesecuritiestables
statementnote4propertyandequipmenttables
statementnote5accruedexpensestables
statementnote9warrantstables
statementnote12sharebasedcompensationplanstables
Operating expenses:
statementnote13fairvaluemeasurementstables
statementnote14incometaxestables
statementnote15commitmentsandcontingenciestables
Litigation receivable
Amount due from a litigation.
statementnote16operatingsegmentsandgeographicinformationtables
statementnote2summaryofsignificantaccountingpoliciescashandcashequivalentsdetails
Revenues
Revenues
statementnote2summaryofsignificantaccountingpoliciescashrestrictedundersecurityagreementsdetails
statementnote2summaryofsignificantaccountingpoliciespropertyandequipmentusefullivesdetails
statementnote2summaryofsignificantaccountingpoliciesrevenuesbymajorcustomersdetails
statementnote2summaryofsignificantaccountingpoliciessharebasedcompensationdetails
Common Stock issuance in settlement of lawsuit
Represents the issuance of common stock in the settlement of a lawsuit.
statementnote2summaryofsignificantaccountingpoliciesweightedaveragefairvalueassumptionsforstockbasedcompensationdetails
optt_IncreaseDecreaseInLitigationPayables
Litigation payable
The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to litigations.
statementnote3marketablesecuritiesmarketablesecuritiesthatmaturewithinoneyeardetails
optt_AggregateMarketValueCommonStock
Aggregate Market Value, Common Stock
The aggregate market value of common stock through a shelf registration that has been meditated through an underwriter.
statementnote4propertyandequipmentcomponentsofpropertyandequipmentdetails
statementnote4propertyandequipmentcapitalleasecommitmentsdetails
Purchase Agreement [Member]
Represents the securities purchase agreement.
statementnote5accruedexpensesaccruedexpensesdetails
statementnote9warrantsfairvalueassumptionsforwarrantsdetails
optt_ClassOfWarrantOrRightExpirationPeriod
Class of Warrant or Right, Expiration Period
Period from date of issuance that the warrant or right expires.
statementnote12sharebasedcompensationplansstockoptionsundertheplansdetails
statementnote12sharebasedcompensationplansnonvestedrestrictedstockundertheplansdetails
optt_CapitalLeaseTerm
Capital Lease, Term
Represent the term of the capital lease.
statementnote13fairvaluemeasurementsfinancialassetsandliabilitiesmeasuredatfairvalueonarecurringbasisdetails
Reimbursement of Out of Pocket and Legal Expenses [Member]
Represents the amount reimbursed to the placement agents for their out of pocket and legal expenses in connection with the offering.
statementnote13fairvaluemeasurementschangesonvalueofwarrantliabilitydetails
statementnote14incometaxescomponentsoflossbeforeincometaxesdetails
statementnote14incometaxeseffectiveincometaxratereconciliationdetails
Stock Incentive Plan 2015 [Member]
Represents the Company's 2015 Omnibus Incentive Plan.
statementnote14incometaxesdeferredtaxassetsanddeferredtaxliabilitiesdetails
Placement Agents [Member]
Represents the persons in connection with the securities purchase agreement.
statementnote15commitmentsandcontingenciesoperatingleasecommitmentsdetails
optt_OperatingLossCarryforwardsLimitation
Operating Loss Carryforwards, Limitation
The ceiling amount of all operating loss carryforwards available to reduce future taxable income.
statementnote16operatingsegmentsandgeographicinformationgeographicsegmentinformationdetails
optt_SharebasedCompensationArrangementBySharebasedPaymentAwardPlanEffectivePeriod
Share-based Compensation Arrangement by Share-based Payment Award, Plan Effective Period
Period from effective date that an equity-based award plan is terminated, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
Notes To Financial Statements
Placement Agent Fees [Member]
Represents the fees associated with the placement agents in the securities purchase agreement.
optt_LitigationSettlementAmountPaidByInsurer
Litigation Settlement, Amount Paid by Insurer
Amount of judgment or settlement paid by the entity's insurer in respect of litigation.
Notes To Financial Statements [Abstract]
Stipulation [Member]
Represents the Stipulation and Agreement of Class Settlement.
Santander Bank [Member]
Cash on deposit at Santander Bank which serves as security for letter of credit.
us-gaap_MarketableSecuritiesCurrent
Marketable securities
Cash flows from investing activities:
Interim Period, Costs Not Allocable [Domain]
Nature of Expense [Axis]
Reported Value Measurement [Member]
Property, Plant and Equipment, Useful Life [Table Text Block]
Tabular disclosure of the useful lives of physical assets used in the normal conduct of business and not intended for resale.
Lease Arrangement, Type [Axis]
Lease Arrangement, Type [Domain]
Cash and Cash Equivalents [Domain]
Unearned revenues
us-gaap_ComprehensiveIncomeNetOfTax
Comprehensive loss attributable to Ocean Power Technologies, Inc.
Cash and Cash Equivalents [Axis]
Legal settlement (in shares)
Stock Issued During Period, Shares, Litigation Settlement
Number of new stock issued for litigation settlement during the period.
us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Line of Credit Facility, Commitment Fee Percentage
Legal settlement
Stock Issued During Period, Value, Litigation Settlement
Equity impact of the value of new stock issued during the period for litigation settlement.
us-gaap_IncreaseDecreaseInAccruedLiabilities
Accrued expenses
Restrictions on Cash and Cash Equivalents [Table Text Block]
optt_PricePerCommonStockAndWarrant
Price Per Common Stock and Warrant
Per unit amount of common stock and warrant issued.
Restricted Cash and Cash Equivalents [Axis]
Monroe Lease [Member]
Represents the lease arrangement of production space located in Monroe Township, New Jersey.
us-gaap_TreasuryStockSharesAcquired
Treasury Stock, Shares, Acquired
Acquisition of treasury stock (in shares)
Preferred stock, shares outstanding (in shares)
Use of Estimates, Policy [Policy Text Block]
optt_OperatingLeasesTenantImprovementAllowanceMaximum
Operating Leases, Tenant Improvement Allowance, Maximum
The maximum amount of tenant improvement allowance under the operating leases.
New Accounting Pronouncements, Policy [Policy Text Block]
Schedule of Cash and Cash Equivalents [Table Text Block]
Product Development [Member]
Primary financial statement caption encompassing product development.
us-gaap_SharesOutstanding
Balance (in shares)
Balance (in shares)
us-gaap_IncreaseDecreaseInAccountsPayable
Accounts payable
Restricted cash
Subsequent Event [Member]
Consolidation, Policy [Policy Text Block]
Related Party [Axis]
optt_DeferredTaxAssetsNetBeforeValuationAllowance
Net deferred tax assets before valuation allowance
Amount of deferred tax assets net of deferred tax liabilities before allocation of valuation allowance.
Subsequent Event Type [Domain]
Subsequent Event Type [Axis]
Related Party [Domain]
George W. Taylor [Member]
The formerly employed by the Company as Executive Vice Chairman and served on the Board of Directors.
Cash and cash equivalents
Cash and Cash Equivalents, at Carrying Value
Cash and cash equivalents, beginning of period
Cash and cash equivalents, end of period
Offering Agreement [Member]
Offering-agreement.
optt_OwnershipPercentage
Ownership Percentage
The percentage of ownership of common stock or equity participation in the investee.
Subsequent Events [Text Block]
Checking and Savings Accounts [Member]
Checking and savings accounts [member]
Barclays Bank Agreement [Member]
Barclays bank agreement [member]
NJBPU Agreement [Member]
NJBPU agreement [member]
us-gaap_AreaOfRealEstateProperty
Area of Real Estate Property
US Department of Energy [Member]
Related to the customer US Department of Energy.
Mitsui Engineering and Ship Building [Member]
Related to the customer Mitsui Engineering and Ship Building.
European Union Waver Port Project [Member]
Related to the customer European Union Waver Port Project.
Current [Member]
Current [member]
Debt Disclosure [Text Block]
us-gaap_FairValueAssumptionsExpectedVolatilityRate
Expected volatility
Stock based compensation
New Jersey Board of Public Utilities 1 [Member]
The entity of New jersey board of public utilities 1
Customer Advances and Deposits Disclosure [Text Block]
Customer Advances And Deposits Disclosure
optt_DeferredCreditsPayableOptionDetails
Deferred Credits Payable Option Details
Deferred credits payable option details
optt_DeferredCreditsPayableMarketDiscountRate
Deferred Credits Payable Market Discount Rate
Deferred Credits Payable Market Discount Rate
optt_DeferredCreditsPayableMarketLiquidatedDamagesRate
Deferred Credits Payable Market Liquidated Damages Rate
Deferred Credits Payable Market Liquidated Damages Rate
Stock Incentive Plan 2006 [Member]
Represents the Company's 2006 Stock Incentive Plan.
Performance-based vesting [Member]
Represents the performance-based vesting requirements.
Revenues, percentage
us-gaap_TreasuryStockValueAcquiredCostMethod
Acquisition of treasury stock
Customer Concentration Risk [Member]
us-gaap_TreasuryStockValue
Treasury stock, at cost; 48,065 and 6,894 shares, respectively
us-gaap_StockholdersEquityNoteStockSplitConversionRatio1
Stockholders' Equity Note, Stock Split, Conversion Ratio
Concentration Risk Type [Domain]
us-gaap_IncreaseDecreaseInOtherOperatingAssets
Other assets
Concentration Risk Type [Axis]
optt_InputTax
Input Tax
Input tax.
Stockholders' Equity Note Disclosure [Text Block]
Sales Revenue, Net [Member]
us-gaap_AllocatedShareBasedCompensationExpense
Allocated Share-based Compensation Expense
Concentration Risk Benchmark [Domain]
Concentration Risk Benchmark [Axis]
Issuance of restricted stock, net (in shares)
Exercised (in shares)
Asia and Australia [Member]
Asia and australia [member]
Issuance of restricted stock, net
us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Change in fair value
us-gaap_IncreaseDecreaseInUnbilledReceivables
Unbilled receivable
us-gaap_IncreaseDecreaseInAccountsReceivable
Accounts receivable
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Forfeited (in shares)
Granted (in shares)
optt_ProceedFromSaleOfLossCarryforwardsAndTaxCredits
Proceed from Sale of Loss Carryforwards and Tax Credits
Amount received from sale of net operating loss carryforwards and other tax credits.
Sale of stock (in shares)
Stock Issued During Period, Shares, New Issues
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]
us-gaap_NoncurrentAssets
Long-lived assets
Sale of stock
us-gaap_DeferredTaxAssetsValuationAllowance
Deferred Tax Assets, Valuation Allowance
Valuation allowance
us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and stockholders’ equity
Accumulated deficit
Retained Earnings (Accumulated Deficit)
Accumulated other comprehensive loss
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]
us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Fair value – April 30, 2016
Fair value – April 30, 2017
Marketable Securities [Table Text Block]
Transfers
us-gaap_DeferredTaxAssetsLiabilitiesNet
Net deferred tax assets
Issuance
Foreign exchange gain (loss)
Foreign exchange loss
Other
Unrealized foreign exchange loss
us-gaap_NumberOfOperatingSegments
Number of Operating Segments
Interest income, net
Accrued expenses
Segment Reporting Disclosure [Text Block]
us-gaap_SecurityDeposit
Security Deposit
Dividend rate
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
Risk-free rate
Foreign Currency Transactions and Translations Policy [Policy Text Block]
Expected life (years) (Year)
Stock compensation
Earnings Per Share, Policy [Policy Text Block]
Other income
Fair Value, Measurements, Recurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block]
Comprehensive Income, Policy [Policy Text Block]
Fair Value, Measurement Frequency [Domain]
Measurement Frequency [Axis]
Income Tax, Policy [Policy Text Block]
Changes in operating assets and liabilities:
Federal and New Jersey research and development tax credits
Deferred Tax Assets, Tax Credit Carryforwards, Research
Restricted cash- long-term
Property, Plant and Equipment [Table Text Block]
Foreign net operating loss carryforwards
Federal net operating loss carryforwards
Property, Plant and Equipment Disclosure [Text Block]
State operating loss carryforwards
us-gaap_OperatingIncomeLoss
Operating loss
Operating loss
Cost of revenues
us-gaap_GrossProfit
Gross profit (loss)
Treasury stock (in shares)
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]
Amendment Flag
Common stock, $0.001 par value; authorized 50,000,000 shares, issued 6,313,996 and 2,352,100 shares, respectively
Change in fair value of warrant liabilities
Fair Value Adjustment of Warrants
Change in fair value of warrant liabilities
Common stock, shares authorized (in shares)
Common Stock, Shares Authorized
us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract
Lessee, Operating Lease, Term of Contract
Common stock, shares issued (in shares)
Other noncurrent assets
Common stock, par value (in dollars per share)
Lessee, Operating Lease, Disclosure [Table Text Block]
Compensation expense related to stock option grants and restricted stock
us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Common Stock, Capital Shares Reserved for Future Issuance
Current Fiscal Year End Date
Document Fiscal Period Focus
Document Fiscal Year Focus
Document Period End Date
Preferred stock, $0.001 par value; authorized 5,000,000 shares, none issued or outstanding
Preferred stock, shares issued (in shares)
Preferred Stock, Shares Issued
Document Type
Depreciation and amortization
Preferred stock, shares authorized (in shares)
Preferred Stock, Shares Authorized
Document Information [Line Items]
Document Information [Table]
Preferred stock par value (in dollars per share)
Preferred Stock, Par or Stated Value Per Share
us-gaap_Depreciation
Depreciation
us-gaap_AssetsCurrent
Total current assets
Entity Public Float
Estimate of Fair Value Measurement [Member]
Entity Filer Category
Entity Current Reporting Status
Entity Voluntary Filers
Entity Well-known Seasoned Issuer
Measurement Basis [Axis]
Portion at Fair Value Measurement [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Entity Central Index Key
Entity Registrant Name
Entity [Domain]
Legal Entity [Axis]
us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Class of Warrant or Right, Exercise Price of Warrants or Rights
us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right
us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Class of Warrant or Right, Number of Securities Called by Warrants or Rights
Other current assets
Other Assets, Current
us-gaap_PaymentsForLegalSettlements
Payments for Legal Settlements
Entity Common Stock, Shares Outstanding (in shares)
Cash paid for interest
Additional paid-in capital
Ocean Power Technologies, Inc. stockholders’ equity:
Revenue Recognition, Policy [Policy Text Block]
Trading Symbol
us-gaap_LettersOfCreditOutstandingAmount
Letters of Credit Outstanding, Amount
Intangible Assets, Finite-Lived, Policy [Policy Text Block]
Certificates of Deposit [Member]
Commitments and contingencies
us-gaap_Liabilities
Total liabilities
Property and equipment, useful life
Cash flows from operating activities:
Accounts Receivable
Statement [Line Items]
AOCI Attributable to Parent [Member]
Property and equipment, useful life (Year)
Fair Value Disclosures [Text Block]
Restricted cash- short-term
Assets Held under Capital Leases [Member]
ASSETS
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash provided by financing activities
Foreign currency translation adjustment
Over-Allotment Option [Member]
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash (used in) provided by investing activities
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash used in operating activities
Sale of Stock [Domain]
Leasehold Improvements [Member]
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Net increase (decrease) in cash and cash equivalents
Sale of Stock [Axis]
Effect of exchange rate changes on cash and cash equivalents
Property, Plant and Equipment, Type [Domain]
Domestic
Property, Plant and Equipment, Type [Axis]
Foreign
Other comprehensive loss
Property, Plant and Equipment, Policy [Policy Text Block]
us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
Total stockholders' equity
Balance
Balance
Unbilled receivables
us-gaap_OperatingLeasesFutureMinimumPaymentsDue
Total
us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter
Thereafter
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears
2021
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears
2022
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears
2019
us-gaap_PaymentsOfStockIssuanceCosts
Payments of Stock Issuance Costs
us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears
2020
us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent
2018
us-gaap_LongTermDebt
Long-term Debt
Financial Instruments [Domain]
Financial Instrument [Axis]
Noncontrolling Interest [Member]
Proceeds from issuance of common stock and related warrants, net of costs
Proceeds from Issuance or Sale of Equity
us-gaap_PaymentsForRepurchaseOfCommonStock
Acquisition of treasury stock
Fair Value, Inputs, Level 2 [Member]
Fair Value, Inputs, Level 1 [Member]
Fair Value, Inputs, Level 3 [Member]
Retained Earnings [Member]
us-gaap_LineOfCredit
Long-term Line of Credit
Additional Paid-in Capital [Member]
Fair Value Hierarchy [Domain]
Treasury Stock [Member]
Fair Value, Hierarchy [Axis]
Proceeds from issuance of common stock, net of costs
Marketable Securities, Policy [Policy Text Block]
Parent [Member]
Equity Component [Domain]
Concentration Risk, Credit Risk, Policy [Policy Text Block]
Common Stock [Member]
Equity Components [Axis]
Supplemental Balance Sheet Disclosures [Text Block]
Preferred Stock [Text Block]
us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
Long-term debt and capital lease obligations
Weighted average shares used to compute basic and diluted net loss per share (in shares)
Basic and diluted net loss per share (in dollars per share)
us-gaap_SharePrice
Share Price
us-gaap_IncomeTaxExaminationPenaltiesAndInterestAccrued
Income Tax Examination, Penalties and Interest Accrued
us-gaap_IncomeTaxExaminationPenaltiesExpense
Income Tax Examination, Penalties Expense
Tax Authority, Spain [Member]
us-gaap_RepaymentsOfLongTermCapitalLeaseObligations
Payment of capital lease obligations
Equipment [Member]
New Jersey Division of Taxation [Member]
U.S. Department of Defense Office of Naval Research [Member]
Related to the customer U.S. Department of Defense Office of Naval Research.
Selling, General and Administrative Expenses [Member]
Scenario, Unspecified [Domain]
Scenario [Axis]
Income Tax Authority, Name [Domain]
Additional investment in subsidiary
Nonmonetary Transaction Type [Domain]
Nonmonetary Transaction Type [Axis]
us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners
Foreign Tax Authority [Member]
Domestic Tax Authority [Member]
Income Tax Authority, Name [Axis]
State and Local Jurisdiction [Member]
Income Tax Authority [Domain]
Income Tax Authority [Axis]
Income Statement Location [Domain]
Income Statement Location [Axis]
optt_ShelfRegistrationAmountOfSecuritiesToOfferAndSale
Shelf Registration Amount Of Securities To Offer And Sale
Amount of stock for offer and sale that has been registered under the shelf registration filing.
Cash and Cash Equivalents, Policy [Policy Text Block]
Maximum [Member]
Basis of Accounting, Policy [Policy Text Block]
Range [Domain]
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]
us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
Less: Net profit attributable to the non-controlling interest in Ocean Power Technologies (Australasia) Pty Ltd.
Minimum [Member]
Customer [Axis]
Significant Accounting Policies [Text Block]
Range [Axis]
us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits
Accounting Policies [Abstract]
Customer [Domain]
us-gaap_LitigationSettlementAmountAwardedToOtherParty
Litigation Settlement, Amount Awarded to Other Party
Statement of Financial Position [Abstract]
Litigation settlement
optt_AffirmativeVotePercentageByStockholders
Affirmative Vote Percentage By Stockholders
Percentage of affirmative votes from the entity's stockholders.
us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest
Comprehensive income attributable to the non-controlling interest in Ocean Power Technologies (Australasia) Pty Ltd.
Stern Lawsuit [Member]
Lawsuit filed by alleged shareholder.
Statement of Cash Flows [Abstract]
Statement of Stockholders' Equity [Abstract]
Corporation [Member]
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]
Legal Entity Type of Counterparty [Domain]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
Total comprehensive loss
Legal Entity of Counterparty, Type [Axis]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
Net loss
Net loss
North America [Member]
Europe [Member]
Geographical [Domain]
Geographical [Axis]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
us-gaap_RepaymentsOfDebt
Payment of debt
us-gaap_OperatingLossCarryforwards
Operating Loss Carryforwards
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Loss before income taxes
us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments
Other
us-gaap_IncomeTaxExpenseBenefit
Income Tax Expense (Benefit)
Income tax benefit
us-gaap_EffectiveIncomeTaxRateContinuingOperations
Income tax benefit
Increase in valuation allowance
Deferred credits payable non-current
Customer Advances or Deposits, Noncurrent
us-gaap_PolicyTextBlockAbstract
Accounting Policies
Major Types of Debt and Equity Securities [Domain]
Statement [Table]
Major Types of Debt and Equity Securities [Axis]
Cash flows from financing activities:
Income Statement [Abstract]
Increase(reduction) in income taxes resulting from:
Contract loss reserve
Other non-deductible expenses
Class of Stock [Axis]
Award Type [Axis]
Equity Award [Domain]
Foreign rate differential
State income taxes, net of federal benefit
us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsResearch
Federal research and development tax credits
Computed expected tax benefit
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
Deferred credits payable current
Customer Advances and Deposits, Current
Reverse Stock Split [Member]
The conversion of a reverse stock split where there is a reduction in the shares outstanding
us-gaap_LiabilitiesCurrent
Total current liabilities
Common Stock, Policy [Policy Text Block]
Disclosure of accounting policy for disclosing common stock issuance and reverse stock splits.
Schedule of Other Assets and Other Liabilities [Table Text Block]
Share-based Compensation, Activity [Table Text Block]
us-gaap_OperatingExpenses
Total operating expenses
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
Litigation payable
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]
Expected dividend yield
us-gaap_DerivativeLiabilitiesCurrent
Derivative Liability, Current
us-gaap_LeaseAndRentalExpense
Operating Leases, Rent Expense
Risk-free interest rate
Expected volatility
Unearned revenue
Expected life (in years) (Year)
Current portion of long-term debt and capital lease obligations
Litigation Case [Domain]
Warrant Liability, Policy [Policy Text Block]
Disclosure of accounting policy for warrant liability.
Litigation Case [Axis]
Warrant Disclosure [Text Block]
The entire disclosure for warrants.
Commitments and Contingencies Disclosure [Text Block]
Maturities of marketable securities
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
Forfeited (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Vested (in dollars per share)
Changes on Value of Warrant Liability [Table Text Block]
Tabular disclosure of pertinent information about the changes on the value of the warrant liability.
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Beginning Balance, issued and unvested (in dollars per share)
Ending Balance, issued and unvested (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number
Beginning Balance, issued and unvested (in shares)
Ending Balance, issued and unvested (in shares)
Income Tax Disclosure [Text Block]
us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Loss on disposal of property, plant and equipment
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Granted (in dollars per share)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Forfeited (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Vested (in shares)
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term
Warrant liabilities
The current portion of warrant liability.
us-gaap_CapitalLeasesFutureMinimumPaymentsDue
Total net future minimum lease payments
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value
Exercisable, weighted average remaining contractual term (Year)
2018
Overnight Repurchase Account [Member]
Represents overnight repurchase account.
Exercisable, weighted average exercise price (in dollars per share)
2019
Exercisable, shares underlying options (in shares)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value
Accrued taxes payable
Balance, weighted average remaining contractual term (Year)
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value
Accounts payable
Computers and Software [Member]
Represents long lived, depreciable assets that are used in the creation, maintenance and utilization of information systems and software applications.
us-gaap_AccruedLiabilitiesCurrent
Accrued expenses
Accrued expenses total
Office Furniture and Equipment [Member]
Represents office furniture and equipment.
Employee incentive payments
Counterparty Name [Domain]
Counterparty Name [Axis]
us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares
us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments
Less; Amount representing interest
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Beginning Balance, weighted average exercise price (in dollars per share)
Ending Balance, weighted average exercise price (in dollars per share)
us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments
Present value of net minimum lease payments
Accrued salary and benefits
Forfeited (in dollars per share)
Granted (in dollars per share)
us-gaap_OtherAccruedLiabilitiesCurrent
Other
Exercised (in dollars per share)
Legal and accounting fees
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Beginning Balance, shares underlying options (in shares)
Ending Balance, shares underlying options (in shares)
OPTA [Member]
Represents the interest in OPTA.
Barclays Bank [Member]
The entity of Barclays bank.
Project costs
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant
Stock Plan 2001 [Member]
Represents stock plan 2001.
LIABILITIES AND STOCKHOLDERS' EQUITY
us-gaap_Assets
Total assets
Total assets
optt_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesGrantsPerParticipant
Share Based Compensation Arrangement By Share Based Payment Award Maximum Number of Shares Grants Per Participant
The highest quantity of shares may be granted to an participant under the plan per calendar year.
optt_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingContractualTerm
Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Contractual Term
Contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
optt_ForeignTaxExaminationRefund
Foreign Tax Examination Refund
The amount of tax refund due to the result of a foreign tax examination.
us-gaap_IncreaseDecreaseInRestrictedCash
Restricted cash
optt_RelatedPartyTransactionTermOfAgreement
Related Party Transaction Term of Agreement
Period of the Executive Transition Agreement under which the executive will receive a monthly consulting fee.
optt_RelatedPartyTransactionMonthlyConsultingFee
Related Party Transaction Monthly Consulting Fee
The amount of the consulting fee that is paid on a reoccurring basis.
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized
us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized
Schedule of Components of Loss Before Income Taxes [Table Text Block]
Tabular disclosure of components of loss before income taxes.
Proceeds of sale of New Jersey tax benefits
The proceeds of a sale of new jersey tax benefits expressed as a percentage in the effective tax rate reconciliation.
Non-vested Restricted Stock [Member]
Business Description and Basis of Presentation [Text Block]
us-gaap_PaymentsToAcquireMachineryAndEquipment
Purchases of equipment
Liquidity, Policy [Policy Text Block]
Disclosure of liquidity accounting policy.
Vesting [Domain]
us-gaap_NetIncomeLoss
Net loss attributable to Ocean Power Technologies, Inc.
Plan Name [Axis]
Selling, general and administrative costs
Vesting [Axis]
Plan Name [Domain]
Service-based Vesting [Member]
Shares which will vest based on service.
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition
us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options
Stock Appreciation Rights (SARs) [Member]
Restricted Stock [Member]
Warrant [Member]
us-gaap_RestrictedCashAndCashEquivalents
Restricted Cash and Cash Equivalents
us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Related Party Transaction, Expenses from Transactions with Related Party
Employee Stock Option [Member]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
Acquisition of equipment pursuant to capital leases
Related Party Transactions Disclosure [Text Block]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]
Statement of Comprehensive Income [Abstract]
Product development costs
Supplemental disclosure of noncash investing activities:
Supplemental schedule of cash flows information:
Investments [Domain]
Investment Type [Axis]
optt_LongTermDebtPaymentTerms1
Long-term Debt Payment Terms
Long-erm debt payment terms
Property and equipment, net
Property and equipment, net
us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Less: accumulated depreciation
us-gaap_PropertyPlantAndEquipmentGross
Property and equipment, gross
us-gaap_CapitalLeasedAssetsGross
Capital Leased Assets, Gross
us-gaap_TableTextBlock
Notes Tables