Document And Entity Information [Abstract] Document And Entity Information Document Information [Table] Document Information [Line Items] Document And Entity Information Document Type Document Type Document Period End Date Document Period End Date Entity File Number Entity Registrant Name Entity Registrant Name Entity Address, Address Line One Entity Address, City or Town Entity Address, Postal Zip Code Entity Address, Country Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Condensed Consolidated Statements of Operations Statement [Table] Statement [Table] Product and Service [Axis] Product and Service [Domain] This member stands for time charter and bareboat revenues. Time Charter And Bareboat Revenues [Member] Time charter and bareboat revenues This member stands for Voyage revenues. Voyage Revenues [Member] Voyage revenues Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account, Class [Domain] Represents the member information Common units of limited partnership interest. Common Units [Member] Common units Common Units Statement [Line Items] Statement Revenues [Abstract] Operating revenues: (Notes 3 and 4) Revenue from Contract with Customer, Excluding Assessed Tax Revenue from contract with customers Gain on Business Interruption Insurance Recovery Loss of hire insurance recoveries (Note 5) Loss of hire insurance payments recorded as a component of total revenues Other Income Other income Revenues Revenues Total revenues Gain (Loss) on Disposition of Property Plant Equipment Net gain from disposal of vessel Gain from disposal of vessel Operating Expenses [Abstract] Operating expenses: It represents the amount of vessel operating expense. Vessel Operating Expenses Vessel operating expenses Amount of expenses and commission. Expenses And Commission Voyage expenses and commission Depreciation Depreciation for the period Depreciation Depreciation General and Administrative Expense General and administrative expenses Operating Expenses Operating expenses Total operating expenses Operating Income (Loss) Operating income Nonoperating Income (Expense) [Abstract] Finance income (expense): (Note 6) Investment Income, Interest Interest income Investment Income, Investment Expense Interest expense (Note 6) Other Nonoperating Income (Expense) Other finance expense (Note 6) Derivative, Gain (Loss) on Derivative, Net Realized and unrealized gain (loss) on derivative instruments (Note 7) Total realized and unrealized gain (loss) on derivative instruments: Foreign Currency Transaction Gain (Loss), before Tax Net gain (loss) on foreign currency transactions Nonoperating Income (Expense) Total finance expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income (loss) before income taxes Income (loss) before income taxes Income Tax Expense (Benefit) Income tax expense (Note 9) Income tax benefit (expense) Income tax (benefit)/expense Net Income (Loss) Attributable to Parent Net income (loss) Net income (loss) Temporary Equity, Net Income Net income (loss) Series A Preferred unitholders' interest in net income (loss) Net Income (Loss) Allocated to General Partners General Partner's interest in net income (loss) Net Income (Loss) Allocated to Limited Partners Limited Partners' interest in net income (loss) Earnings Per Share, Basic [Abstract] Earnings per unit (Basic): (Note 16) Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic, Net of Tax Earnings per unit (basic) Earnings per unit (basic) (in dollars per share) Net Income (Loss), Per Outstanding General Partnership Unit, Net of Tax General Partner General Partner unit (in dollars per share) Earnings Per Share, Diluted [Abstract] Earnings per unit (Diluted): (Note 16) Net Income (Loss), Net of Tax, Per Outstanding Limited Partnership Unit, Diluted Earnings per unit (diluted) (in dollars per share) Condensed Consolidated Statements of Comprehensive Income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other comprehensive income Other comprehensive income, net of tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income (loss) Condensed Consolidated Balance Sheets Represents the member information pertaining to Class B Units. Class B Units [Member] Class B Units Class B unit Assets [Abstract] ASSETS Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents (Note 8) Other Receivables, Net, Current Other receivables Amounts due from related parties (Note 14) Other Receivable, after Allowance for Credit Loss, Current, Related Party [Extensible Enumeration] Inventory, Net Inventories (Note 11) Total inventory Derivative Asset, Current Current derivative assets Derivative assets (Notes 7 and 8) Other Assets, Current Other current assets (Note 18) Total other current assets Other current assets from related parties Assets, Current Total current assets Non-current assets: Long-term assets: Property, Plant and Equipment, Net Net Vessels, ending balance Net Vessels, beginning balance Vessels, net of accumulated depreciation (Notes 10 and 21) Operating Lease, Right-of-Use Asset Right-of-use assets Right-of-use assets (Note 4) Deferred Income Tax Assets, Net Deferred tax assets (Note 9) Derivative Asset, Noncurrent Derivative assets (Notes 7 and 8) Non-current derivative assets Accrued Investment Income Receivable Accrued income Other Assets, Noncurrent Other long-term assets (Note 20) Assets, Noncurrent Total Long-term assets Assets Total assets Liabilities and Equity [Abstract] LIABILITIES AND EQUITY Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Trade accounts payable Trade accounts payables to related parties Accrued Liabilities, Current Total accrued expenses Accrued expenses (Note 19) Long-term Debt, Current Maturities Current portion of long-term debt Current portion of long-term debt (Notes 8 and 13) Operating Lease, Liability, Current Current lease liabilities (Note 4) Derivative Liability, Current Current derivative liabilities Current portion of derivative liabilities (Note 8) Taxes Payable, Current Income taxes payable (Note 9) Current portion of the amount after amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. Below Market Lease Net Current Current portion of contract liabilities (Note 12) Contract with Customer, Liability, Current Prepaid charter and deferred revenue Other Liabilities, Current Amount due to related parties (Note 14) Other Liability, Current, Related Party, Type [Extensible Enumeration] Liabilities, Current Total current liabilities Liabilities, Noncurrent [Abstract] Long-term liabilities: Long-term Debt, Excluding Current Maturities Long-term debt (Notes 8 and 13) Long-term debt, less current installments, and unamortized deferred loan issuance costs Operating Lease, Liability, Noncurrent Lease liabilities (Note 4) Derivative Liability, Noncurrent Derivative liabilities (Notes 7 and 8) Non-current derivative liabilities Noncurrent portion of the amount after amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. Below Market Lease, Net, Noncurrent Contract liabilities (Note 12) Deferred Income Tax Liabilities, Net Deferred tax liabilities (Note 9) Amount of deferred revenue related to leases classified as non-current. Deferred Revenue, Leases Deferred revenues Amount of other long term liabilities. Other Long Term Liabilities Other long-term liabilities (Note 20) Liabilities, Noncurrent Total long-term liabilities Liabilities Total liabilities Commitments and Contingencies. Commitments and contingencies (Note 15) Temporary Equity, Carrying Amount, Attributable to Parent Convertible preferred units, ending balance Convertible preferred units, beginning balance Series A Convertible Preferred Units Stockholders' Equity Attributable to Parent [Abstract] Equity: Partners' Capital, Including Portion Attributable to Noncontrolling Interest [Abstract] Partners' capital: Limited Partners' Capital Account Common unitholders General Partners' Capital Account General partner interest Partners' Capital Total partners' capital Liabilities and Equity Total liabilities and equity Limited Partners' Capital Account, Units Issued Limited partners' capital account, units issued Limited Partners' Capital Account, Units Outstanding Limited partners' capital account, units outstanding Number of common units and subordinated units outstanding General Partners' Capital Account, Units Issued General partners' capital account, units issued General Partners' Capital Account, Units Outstanding General partners' capital account, units outstanding Number of general partner units outstanding Condensed Consolidated Statements of Changes in Partners' Capital Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] General Partner Unit General Partner General Partner units Amount of partners capital value. Partners Capital Value Ending balance Beginning balance Amount of earnings (loss) before distributed and undistributed earnings allocated to participating securities for the basic earnings (loss) per share or per unit calculation under the two-class method. Earnings (Loss) Before Distributed And Undistributed Earnings Allocated To Participating Securities, Basic Net income (loss) Net income (loss) attributable to the unitholders of KNOT Offshore Partners LP Partners' Capital Account, Distributions Cash distributions Dividends, Preferred Stock, Cash Cash distributions Condensed Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] OPERATING ACTIVITIES Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income (loss) to cash provided by operating activities: Amount of amortization of contract liability. Amortization Of Contract Liability Amortization of contract intangibles / liabilities Amount of amortization of deferred revenue. Amortization Of Deferred Revenue Amortization of deferred revenue Amortization of Debt Issuance Costs Amortization of debt issuance cost and fair value of debt assumed Amortization of deferred debt issuance cost Amount of dry docking expenditures. Dry Docking Expenditures Drydocking expenditure Income Taxes Paid Income taxes paid The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, as an adjustment to reconcile net income to cash provided by (used in) operating activities. Unrealized Gain (Loss) on Derivatives, Cash Flow Impact Unrealized (gain) loss on derivative instruments Foreign Currency Transaction Gain (Loss), Unrealized Unrealized gain on foreign currency transactions Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Due from Related Parties Decrease (increase) in amounts due from related parties Increase (Decrease) in Inventories Decrease (increase) in inventories Increase (Decrease) in Other Current Assets Decrease (increase) in other current assets Increase (Decrease) in Deferred Revenue Decrease (increase) in accrued income Increase (Decrease) in Accounts Payable, Trade Increase (decrease) in trade accounts payable Increase (Decrease) in Accrued Liabilities Increase (decrease) in accrued expenses Increase (Decrease) in Contract with Customer, Liability Increase (decrease) prepaid charter Increase (Decrease) in Due to Related Parties Increase (decrease) in amounts due to related parties Net Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] INVESTING ACTIVITIES Payments for (Proceeds from) Productive Assets Additions to vessel and equipment Proceeds from Derivative Instrument, Investing Activities Proceeds from asset swap (net cash) Net Cash Provided by (Used in) Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] FINANCING ACTIVITIES Repayments of Long-term Debt Repayment of long-term debt Payments of Debt Issuance Costs Payment of debt issuance cost Payments of Ordinary Dividends Cash distributions Net Cash Provided by (Used in) Financing Activities Net cash used in financing activities Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Effect of exchange rate changes on cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents at the end of the period Cash and cash equivalents at the beginning of the period Interest Paid, Excluding Capitalized Interest, Operating Activities Amount of interests paid Description of Business Business Description and Basis of Presentation [Text Block] Description of Business Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Segment Information Segment Reporting Disclosure [Text Block] Segment Information Operating Leases The entire disclosure of information about leases. Lease Disclosure [Text Block] Operating Leases Insurance proceeds Business Insurance Recoveries [Text Block] Insurance proceeds Other Finance Expenses Interest Income and Interest Expense Disclosure [Text Block] Other Finance Expenses Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments Fair Value Measurements Fair Value Disclosures [Text Block] Fair Value Measurements Income Taxes Income Tax Disclosure [Text Block] Income Taxes Vessels and Equipment Property, Plant and Equipment Disclosure [Text Block] Vessels and Equipment Inventory Inventory Disclosure [Text Block] Inventory N/A Contract Liabilities The entire disclosure for contract liability. Contract Liabilities Disclosure [Text Block] Contract Liabilities Long-Term Debt. Long-term Debt [Text Block]. Long-Term Debt Related Party Transactions Related Party Transactions Disclosure [Text Block] Related Party Transactions Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Earnings per Unit and Cash Distributions Earnings Per Share [Text Block] Earnings per Unit and Cash Distributions Unit Activity Partners' Capital Notes Disclosure [Text Block] Unit Activity Trade Accounts Receivable and Other Current Assets Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Trade Accounts Receivable and Other Current Assets Accrued expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued expenses N/A. Emission Trading System The entire disclosure for emissions trading system. Emissions Trading System [Text Block] Emission Trading System