Changes in Accumulated Other Comprehensive Income (Loss) - Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ 353,396
Other Comprehensive Income	2,647	$ 2,729
Amounts reclassified from accumulated other comprehensive loss	198	172
Balance at end of period	369,833
Loss reclassified from AOCI for defined benefit pension plans	200	200
Tax benefit reclassified from AOCI for defined benefit pension plans	100	100
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	(17,303)	(45,049)
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 Income	2,545	2,729
Amounts reclassified from accumulated other comprehensive loss	0	0
Balance at end of period	324	(25,156)
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 Income	0	0
Amounts reclassified from accumulated other comprehensive loss	198	172
Balance at end of period	(17,851)	(19,893)
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 Income	102	0
Amounts reclassified from accumulated other comprehensive loss	0	0
Balance at end of period	$ 224	$ 0