Derivative Instruments and Hedging Activities - Gain (Loss) for Derivative Instruments Not Designated or Qualifying as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gains (losses)			$ 34,178	$ (18,553)
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)	$ 101	$ (1,327)	3,849	(30,314)
Foreign currency exchange gain (loss) (notes 8 and 11)	2,767	(7,853)	6,884	(14,738)
Unrealized gains (losses)			13,125	(10,697)
Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)				(38,760)
Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			(30,329)	(11,761)
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)			3,849	(30,314)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			34,178	(18,553)
Interest rate swap agreements \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(3,919)	(4,947)	(12,317)	(11,520)
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)	101	(1,327)	21,861	(30,275)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net	4,020	3,620	34,178	(18,755)
Foreign Exchange Forward [Member] \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			0	(241)
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)			0	(39)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			0	202
Cross currency swap agreements \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(1,595)	(1,669)
Unrealized gains (losses)	(3,952)	1,490
Cross-currency swap agreements termination \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign currency exchange gain (loss) (notes 8 and 11)			0	(33,844)
Realized gains (losses)			0	(33,844)
Unrealized gains (losses)			0	0
Cross-currency swap agreements \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)			(5,318)	(40,929)
Foreign currency exchange gain (loss) (notes 8 and 11)	$ (5,547)	$ (179)	(5,318)	(7,085)
Realized gains (losses)			(4,233)	(4,916)
Unrealized gains (losses)			(1,085)	(2,169)
Interest rate swaps terminated \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			(18,012)	0
Realized and unrealized gain (loss) on non-designated derivative instruments (note 11)			(18,012)	0
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			$ 0	$ 0

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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 and unrealized 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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