Derivative Instruments and Hedging Activities - Schedule of Estimated Gross Fair Values of Derivative Instruments and Their Classification on Consolidated Balance Sheet (Details) - Interest Rate Swap Agreements - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedges
Liabilities:
Derivative liabilities	$ 13,266	$ 20,377
Derivatives Not Designated as Hedging Instruments
Liabilities:
Derivative liabilities	10,582	16,260
Current Portion of Long-term Liabilities | Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedges
Liabilities:
Current portion of long-term liabilities	7,360	8,205
Current Portion of Long-term Liabilities | Derivatives Not Designated as Hedging Instruments
Liabilities:
Current portion of long-term liabilities	5,873	6,548
Other Long-term Liabilities | Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedges
Liabilities:
Other long-term liabilities	5,906	12,172
Other Long-term Liabilities | Derivatives Not Designated as Hedging Instruments
Liabilities:
Other long-term liabilities	$ 4,709	$ 9,712