Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 301,355	$ 49,380	$ 121,864
Other comprehensive loss:
Adoption of new accounting standards	0	0	408
Market value adjustments on interest rate swaps, net of tax	(24,975)	(33,912)	(10,377)
Reclassification adjustments for gains on terminated interest rate swap included in net income	0	67	0
Foreign currency translation adjustments	23,664	6,903	(33,767)
Supplemental benefit plans adjustments, net of tax	(2,049)	(3,959)	1,679
Total other comprehensive loss	(3,360)	(31,035)	(42,057)
Comprehensive income	$ 297,995	$ 18,345	$ 79,807