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	Dec. 31, 2020	Dec. 31, 2019
Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedging
Liabilities:
Derivative liabilities	$ 20,377	$ 16,238
Derivatives Not Designated as Hedging Instruments
Liabilities:
Derivative liabilities	16,260
Current Portion of Long-term Liabilities | Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedging
Liabilities:
Current portion of long-term liabilities	8,205	4,947
Current Portion of Long-term Liabilities | Derivatives Not Designated as Hedging Instruments
Liabilities:
Current portion of long-term liabilities	6,548
Other Long-term Liabilities | Derivatives Designated as Effective Hedging Instruments | Cash Flow Hedging
Liabilities:
Other long-term liabilities	12,172	$ 11,291
Other Long-term Liabilities | Derivatives Not Designated as Hedging Instruments
Liabilities:
Other long-term liabilities	$ 9,712