Derivative Instruments and Hedging Activities - Gain (Loss) for Derivative Instruments Not Designated or Qualifying as Hedging Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	$ (10,228)	$ (26,855)	$ (18,757)
Unrealized gains (losses)	(3,133)	30,133	13,448
Unrealized gains (losses)	(2,805)	7,525	(23,153)
Total	(13,361)	3,278	(5,309)
Interest rate swap agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(10,081)	(14,654)	(18,825)
Unrealized gains (losses)	(2,891)	31,061	12,393
Total	(12,972)	16,407	(6,432)
Interest rate swap and swaption agreements termination
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	0	(13,681)	(610)
Unrealized gains (losses)	0	0	0
Total	0	(13,681)	(610)
Interest rate swaption agreements
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	0	0	0
Unrealized gains (losses)	0	2	945
Total	0	2	945
Foreign currency forward contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(147)	0	0
Unrealized gains (losses)	(202)	0	0
Total	(349)	0	0
Toledo Spirit time-charter derivative
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	0	1,480	678
Unrealized gains (losses)	(40)	(930)	110
Total	(40)	550	788
Cross currency swap agreements \| Foreign currency gain (loss)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(5,061)	(6,533)	(9,344)
Unrealized gains (losses)	(13,239)	21,240	49,047
Total	(18,300)	14,707	39,703
Cross currency swap agreements termination \| Foreign currency gain (loss)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	0	(42,271)	(25,733)
Unrealized gains (losses)	0	0	0
Total	0	(42,271)	(25,733)
Cross-currency swap agreements \| Foreign currency gain (loss)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(5,061)	(48,804)	(35,077)
Unrealized gains (losses)	(13,239)	21,240	49,047
Total	$ (18,300)	$ (27,564)	$ 13,970

Derivative instruments not designated as hedging instruments realized gain (loss) net.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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