Accumulated Other Comprehensive Income (Loss) - Changes in Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss)
Balance			$ 381,143
Total other comprehensive income (loss)	$ 8,801	$ (2,668)	11,215	$ 163
Balance	395,978		395,978
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss)
Balance			(53,599)	(41,630)
Other comprehensive income (loss) before reclassifications			10,181	(937)
Amounts reclassified from other comprehensive income (loss)			1,034	1,100
Total other comprehensive income (loss)			11,215	163
Balance	(42,384)	(41,467)	(42,384)	(41,467)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss)
Balance			(22,026)	(11,070)
Other comprehensive income (loss) before reclassifications			11,891	(311)
Total other comprehensive income (loss)			11,891	(311)
Balance	(10,135)	(11,381)	(10,135)	(11,381)
Defined Benefit Pension Plan Adjustments
Accumulated Other Comprehensive Income (Loss)
Balance			(32,373)	(30,474)
Other comprehensive income (loss) before reclassifications			(494)	241
Amounts reclassified from other comprehensive income (loss)	544	481	1,086	1,022
Total other comprehensive income (loss)			592	1,263
Balance	(31,781)	(29,211)	(31,781)	(29,211)
Derivatives
Accumulated Other Comprehensive Income (Loss)
Balance			800	(86)
Other comprehensive income (loss) before reclassifications			(1,216)	(867)
Amounts reclassified from other comprehensive income (loss)			(52)	78
Total other comprehensive income (loss)			(1,268)	(789)
Balance	$ (468)	$ (875)	$ (468)	$ (875)