Accumulated Other Comprehensive Income (Loss) - Changes in Components (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss)
Balance			$ 393,991
Total other comprehensive income (loss)	$ 844	$ (2,546)	1,007	$ (8,679)
Balance	401,778		401,778
Accumulated Other Comprehensive Income (Loss).
Accumulated Other Comprehensive Income (Loss)
Balance			(41,630)	(27,510)
Other comprehensive income (loss) before reclassifications			(1,065)	(9,361)
Amounts reclassified from other comprehensive income (loss)			2,072	682
Total other comprehensive income (loss)			1,007	(8,679)
Balance	(40,623)	(36,189)	(40,623)	(36,189)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss)
Balance			(11,070)	1,943
Other comprehensive income (loss) before reclassifications			(595)	(9,462)
Total other comprehensive income (loss)			(595)	(9,462)
Balance	(11,665)	(7,519)	(11,665)	(7,519)
Defined Benefit Pension Plan Adjustments
Accumulated Other Comprehensive Income (Loss)
Balance			(30,474)	(30,358)
Other comprehensive income (loss) before reclassifications			289	103
Amounts reclassified from other comprehensive income (loss)			2,002	1,357
Total other comprehensive income (loss)			2,291	1,460
Balance	(28,183)	(28,898)	(28,183)	(28,898)
Derivatives
Accumulated Other Comprehensive Income (Loss)
Balance			(86)	905
Other comprehensive income (loss) before reclassifications			(759)	(2)
Amounts reclassified from other comprehensive income (loss)			70	(675)
Total other comprehensive income (loss)			(689)	(677)
Balance	$ (775)	$ 228	$ (775)	$ 228