Other Comprehensive Income (Loss) Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances				$ 544,020
Total other comprehensive income (loss)		$ (1,980)	$ 3,620	(1,550)		$ 7,660
Balances		607,490		607,490
Other Comprehensive Income (Loss), Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax				(500)		400
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax				900		200
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax						1,900
Defined Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances				(10,450)		(12,120)
Net unrealized gains (losses) arising during the period				0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(3,030)	[1]	(500)	[2]
Total other comprehensive income (loss)				3,030		500
Balances		(7,420)	(11,620)	(7,420)		(11,620)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances						(2,520)
Net unrealized gains (losses) arising during the period	[3]					(580)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]					(3,100)
Total other comprehensive income (loss)						2,520
Balances			0			0
Accumulated Net Gain (Loss) from Hedges Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances				(3,170)
Net unrealized gains (losses) arising during the period	[4]			1,720
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				0
Total other comprehensive income (loss)				1,720
Balances		(1,450)		(1,450)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances				(3,710)		(9,760)
Net unrealized gains (losses) arising during the period				(6,300)		4,640
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				0		0
Total other comprehensive income (loss)				(6,300)		4,640
Balances		(10,010)	(5,120)	(10,010)		(5,120)
Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances				(17,330)		(24,400)
Net unrealized gains (losses) arising during the period				(4,580)		4,060
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(3,030)		(3,600)
Total other comprehensive income (loss)				(1,550)		7,660
Balances		$ (18,880)	$ (16,740)	$ (18,880)		$ (16,740)

[1] Defined benefit plans, net of income tax of approximately $0.9 million. See Note 14, "Defined Benefit Plans," for further details.

[2] Defined benefit plans, net of income tax of approximately $0.2 million. See Note 14, "Defined Benefit Plans," for further details. Derivative instruments, net of income tax of approximately $1.9 million. See Note 9, "Derivative Instruments," for further details.

[3] Derivative instruments, net of income tax of approximately $0.4 million. See Note 9, "Derivative Instruments," for further details.

[4] Derivative instruments, net of income tax of approximately $0.5 million. See Note 9, "Derivative Instruments," for further details.