Changes in Accumulated Other Comprehensive Income (Loss) - Summary (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ 353,396
Other comprehensive (loss) income	(9,173)	$ 23,944
Amounts reclassified from accumulated other comprehensive loss	595	516
Balance at end of period	377,049
Loss reclassified from AOCI for defined benefit pension plans	600	500
Tax benefit reclassified from AOCI for defined benefit pension plans	200	300
Total Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(20,148)	(47,950)
Balance at end of period	(28,726)	(23,490)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(2,221)	(27,885)
Other comprehensive (loss) income	(9,262)	23,951
Amounts reclassified from accumulated other comprehensive loss	0	0
Balance at end of period	(11,483)	(3,934)
Defined Benefit Pension Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(18,049)	(20,065)
Other comprehensive (loss) income	0	0
Amounts reclassified from accumulated other comprehensive loss	595	516
Balance at end of period	(17,454)	(19,549)
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	122	0
Other comprehensive (loss) income	89	(7)
Amounts reclassified from accumulated other comprehensive loss	0	0
Balance at end of period	$ 211	$ (7)