Stockholders' Equity and Accumulated Other Comprehensive Income - Summary (Details) - USD ($) $ in Thousands	3 Months Ended					5 Months Ended	9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	May 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 253,262	$ 318,420	$ 387,105		$ 369,275	$ 369,275	$ 318,420	$ 369,275
Comprehensive (loss) income, net of tax	(5,477)		(5,849)				(72,474)	10,773
Stock repurchased	(23)		(7)				(31)	(62)
Stock issued under employee plans	0		5				4	5
Stock-based compensation expense	551		417				2,006	1,611
Stock issued to directors	0		0				388	252
Balance at end of period	248,313		381,671	$ 387,105			248,313	$ 381,671
Accounting Standards Update								us-gaap:AccountingStandardsUpdate201409Member
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	253,262	318,420	387,105		369,275	369,275	318,420	$ 369,275
Net gain (loss) on foreign currency translation	8,245		(8,726)				3,434	(6,396)
Balance at end of period	248,313		381,671	387,105			248,313	381,671
Decrease in contract assets							1,059
Taxes on unrealized losses on the fair value of hedging activities	800		100				1,000	700
Impact of de-designation of interest rate swap agreement	200						300
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	0	0	0		(183)	(183)	0	(183)
Balance at end of period				0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	0	0	0		(183)	(183)	0	(183)
Balance at end of period				0
Cumulative Effect, Period of Adoption, Adjustment | Revision of Prior Period, Error Correction, Adjustment | Accounting Standards Update 2014-09
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period					(200)	(200)		(200)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period					(200)	(200)		(200)
Decrease in contract assets					200
Total accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at end of period	(24,465)		(31,860)				(24,465)	(31,860)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at end of period	(24,465)		(31,860)				(24,465)	(31,860)
Foreign currency translation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(22,833)	(18,022)	(16,128)		(18,458)	(18,458)	(18,022)	(18,458)
Balance at end of period	(14,588)		(24,854)	(16,128)			(14,588)	(24,854)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(22,833)	(18,022)	(16,128)		(18,458)	(18,458)	(18,022)	(18,458)
Net gain (loss) on foreign currency translation	8,245		(8,726)				3,434	(6,396)
Other comprehensive income (loss), net of tax	8,245		(8,726)				3,434	(6,396)
Balance at end of period	(14,588)		(24,854)	(16,128)			(14,588)	(24,854)
Pension and other postretirement benefit plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(2,749)	(3,080)	(2,879)		(22,253)	(22,253)	(3,080)	(22,253)
Balance at end of period	(2,798)		(2,858)	(2,879)			(2,798)	(2,858)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(2,749)	(3,080)	(2,879)		(22,253)	(22,253)	(3,080)	(22,253)
Amounts reclassified from accumulated other comprehensive income	(49)		21				282	19,395
Other comprehensive income (loss), net of tax	(49)		21				282	19,395
Balance at end of period	(2,798)		(2,858)	(2,879)			(2,798)	(2,858)
Loss reclassified from AOCI for defined benefit pension plans	100		100			400	100	100
Tax benefit reclassified from AOCI for defined benefit pension plans	100		100			100	100	100
Settlement reclassified from AOCI before tax		400		19,000
Tax benefit from settlement reclassified from AOCI		100		11,500
Unrealized gain/(loss) on derivative instruments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(5,116)	(4,877)	(4,000)		(1,974)	(1,974)	(4,877)	(1,974)
Balance at end of period	(7,079)		(4,148)	(4,000)			(7,079)	(4,148)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(5,116)	$ (4,877)	(4,000)		$ (1,974)	$ (1,974)	(4,877)	(1,974)
Net loss on derivative instruments	(2,669)		(148)				(3,306)	(2,174)
Amounts reclassified from accumulated other comprehensive income	706		0				1,104	0
Other comprehensive income (loss), net of tax	(1,963)		(148)				(2,202)	(2,174)
Balance at end of period	$ (7,079)		$ (4,148)	$ (4,000)			$ (7,079)	$ (4,148)