Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance - January 1	$ (569,430)	$ (501,624)
Other comprehensive income (loss) before reclassifications	(15,775)	(74,936)
Amounts reclassified from AOCL	6,009	7,130
Other comprehensive income (loss)	(9,766)	(67,806)	$ 119,753
Balance - December 31	(579,196)	(569,430)	(501,624)
Accumulated net loss from net investment hedge, net of tax	12,100	17,200
Net of tax	(6,009)	(7,130)
Foreign Currency Translation Items
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance - January 1	(447,925)	(384,779)
Other comprehensive income (loss) before reclassifications	6,561	(63,146)
Amounts reclassified from AOCL	0	0
Other comprehensive income (loss)	6,561	(63,146)
Balance - December 31	(441,364)	(447,925)	(384,779)
Net of tax	0	0
Pension and other post-retirement effects
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance - January 1	(120,647)	(115,755)
Other comprehensive income (loss) before reclassifications	(22,523)	(12,022)
Amounts reclassified from AOCL	6,009	7,130
Other comprehensive income (loss)	(16,514)	(4,892)
Balance - December 31	(137,161)	(120,647)	(115,755)
Amount of settlement of reclassification adjustment from accumulated other comprehensive income (loss)	(859)	983
Tax benefit	1,887	1,224
Net of tax	(6,009)	(7,130)
Cash flow hedging activity
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance - January 1	(858)	(1,090)
Other comprehensive income (loss) before reclassifications	187	232
Amounts reclassified from AOCL	0	0
Other comprehensive income (loss)	187	232
Balance - December 31	(671)	(858)	(1,090)
Net of tax	0	0
Noncontrolling Interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss)	579	668	438
Foreign currency translation adjustments, attributable to noncontrolling interest	5,100	4,500	$ 3,800
Amortization of actuarial losses
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Reclassification from AOCI, before tax	(6,608)	(9,140)
Prior service costs
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Reclassification from AOCI, before tax	$ (429)	$ (197)