Derivative Financial Instruments - Changes in Fair Value of Derivative Contracts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Net loss recognized in other comprehensive loss	$ 6,919	$ 6,071	$ (2,124)
Gain recognized in earnings	(600)	2,200	(200)
Interest rate swap agreements
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Gain recognized in earnings	(145)	(225)
Derivative contracts
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Beginning balance	9,238	3,548
Loss recognized in other comprehensive loss	8,465	6,131
Amounts reclassified from other comprehensive loss to earnings	(1,569)	(216)
Net loss recognized in other comprehensive loss	6,896	5,915
Ending balance	$ 15,989	$ 9,238	$ 3,548