Derivative Instruments and Hedging Activities - Effective Portion of Gains (Losses) on Interest Rate Swap Agreements (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Unrealized loss on qualifying cash flow hedging instruments	$ (959)	$ (19,576)	$ (69,593)	$ (71,828)
Interest Expense
Derivative [Line Items]
Effective Portion Recognized in AOCI	616		(9,610)
Effective Portion Reclassified from AOCI	$ (835)		$ (1,469)
Unrealized loss on qualifying cash flow hedging instruments		(2,244)		(9,646)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		$ 22		$ (430)

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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