Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016		Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, Beginning of Period				$ 635,786
Other comprehensive income (loss) before reclassifications (4)				22,649		$ 6,605
Actuarial net gain (loss) incurred in the fiscal year				35
Amounts reclassified from accumulated other comprehensive (income) loss				258		116
Other comprehensive income		$ 6,171	$ 1,442	22,942	[1]	6,721	[2]
Balance, End of Period		751,104		751,104
AOCI, Pension and other postretirement benefit plans, tax		9,122	9,821	9,122		9,821		$ 9,160	$ 9,879
AOCI, Cumulative changes in net gain (loss) from cash flow hedges, tax		151	0	151		0		$ 0	$ 5
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, Beginning of Period				(46,446)		(41,365)
Other comprehensive income (loss) before reclassifications (4)				23,136		6,605
Actuarial net gain (loss) incurred in the fiscal year				0
Amounts reclassified from accumulated other comprehensive (income) loss				0		0
Other comprehensive income				23,136	[1]	6,605	[2]
Balance, End of Period		(23,310)	(34,760)	(23,310)		(34,760)
Funded status of pension plans and other postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, Beginning of Period	[3]			(45,816)		(47,082)
Other comprehensive income (loss) before reclassifications (4)	[3]			0		0
Actuarial net gain (loss) incurred in the fiscal year	[3]			35
Amounts reclassified from accumulated other comprehensive (income) loss	[3]			36		105
Other comprehensive income	[3]			71	[1]	105	[2]
Balance, End of Period	[3]	(45,745)	(46,977)	(45,745)		(46,977)
Reclassification from AOCI, Current Period, Tax				58		38
Unrealized gain (loss) on derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, Beginning of Period	[4]			0		(11)
Other comprehensive income (loss) before reclassifications (4)	[4]			(487)
Actuarial net gain (loss) incurred in the fiscal year	[4]			0
Amounts reclassified from accumulated other comprehensive (income) loss	[4]			222		11
Other comprehensive income	[4]			(265)	[1]	11	[2]
Balance, End of Period	[4]	(265)	0	(265)		0
Reclassification from AOCI, Current Period, Tax				5		(151)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, Beginning of Period				(92,262)		(88,458)
Other comprehensive income				22,942
Balance, End of Period		$ (69,320)	$ (81,737)	$ (69,320)		$ (81,737)

[1] Net of taxes of $38 and $(151) for the pension plans and postretirement benefits and unrealized gain (loss) on derivatives, respectively.

[2] Net of taxes of $58 and $5 for the pension plans and postretirement benefits and unrealized gain (loss) on derivatives, respectively.

[3] Net of taxes of $9,122 and $9,160 as of September 30, 2017 and December 31, 2016, respectively. Net of taxes of $9,821 and $9,879 as of September 30, 2016 and December 31, 2015, respectively.

[4] Net of taxes of $151 and $0 as of September 30, 2017 and December 31, 2016, respectively. Net of taxes of $0 and $5 as of September 30, 2016 and December 31, 2015, respectively.