Other Comprehensive Loss - Related Tax Effects Allocated to Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Amortization of actuarial losses, before tax amount	$ (551)	$ 2,613	$ (1,105)	$ 1,808
Derivative instruments, before tax amount	1,443	(17)	(2,045)	322
Cumulative translation adjustment, before tax amount	1,920	233	(2,885)	338
Total other comprehensive income (loss), before tax amount	2,812	2,829	(6,035)	2,468
Amortization of actuarial losses, tax expense	105	(874)	212	(719)
Derivative instrument, tax expense	(339)	0	371	0
Cumulative translation adjustment, tax expense	0	0	0	0
Total other comprehensive income (loss), tax expense	234	874	(583)	719
Amortization of actuarial losses, after tax amount	(446)	1,739	(893)	1,089
Derivative instrument, after tax amount	1,104	(17)	(1,674)	322
Cumulative translation adjustment, after tax amount	1,920	233	(2,885)	338
Other comprehensive income (loss)	$ 2,578	$ 1,955	$ (5,452)	$ 1,749