Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 944,277	$ 860,716	$ 934,336	$ 881,589
Other comprehensive income (loss) before reclassifications		(14,992)	18,527	(21,344)	(16,159)
Amounts reclassified from OCI		(240)	(205)	9,282	(7,235)
Ending balance		939,392	896,785	939,392	896,785
Accumulated Other Comprehensive (Loss) Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(155,921)	(204,724)	(159,091)	(163,008)
Ending balance		(171,153)	(186,402)	(171,153)	(186,402)
Cash Flow Hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	817	(912)	749	(199)
Other comprehensive income (loss) before reclassifications	[1]	(115)	889	729	(995)
Amounts reclassified from OCI	[1]	(292)	209	(1,068)	1,380
Ending balance	[1]	410	186	410	186
Pension Items [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	(1,861)	(656)	(1,965)	(672)
Other comprehensive income (loss) before reclassifications	[1]	0	0	0	0
Amounts reclassified from OCI	[1]	52	8	156	24
Ending balance	[1]	(1,809)	(648)	(1,809)	(648)
Foreign Currency Items [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(154,877)	(203,156)	(157,875)	(162,137)
Other comprehensive income (loss) before reclassifications		(14,877)	17,638	(22,073)	(15,164)
Amounts reclassified from OCI		0	(422)	10,194	(8,639)
Ending balance		$ (169,754)	$ (185,940)	$ (169,754)	$ (185,940)

[1] Cash Flow Hedges and Pension Items are net of tax.