Derivative Financial Instruments - Changes in Fair Value of Derivative Contracts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Net loss recognized in other comprehensive loss	$ 526	$ 3,493	$ 8,740	$ 5,667
Gain recognized in earnings	(400)	500	700	1,100
Derivative contracts
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Beginning balance	17,415	5,692	9,238	3,548
Loss recognized in other comprehensive loss	928	3,460	9,284	5,590
Amounts reclassified from other comprehensive loss to earnings	(425)	42	(567)	103
Net loss recognized in other comprehensive loss	503	3,502	8,717	5,693
Ending balance	17,881	9,146	17,881	9,146
Interest rate swap agreements
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax:
Gain recognized in earnings	$ (37)	$ (48)	$ (74)	$ (95)