Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Interest Rate Cap [Member]	Interest Rate Swap [Member]	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock (0.01 Par) [Member]	Common Stock (0.01 Par) [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings (Accumulated Deficit) Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock at Cost [Member]	Treasury Stock at Cost [Member] Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Loss [Member]	Accumulated Other Comprehensive Loss [Member] Interest Rate Cap [Member]	Accumulated Other Comprehensive Loss [Member] Interest Rate Swap [Member]	Accumulated Other Comprehensive Loss [Member] Cumulative Effect, Period of Adoption, Adjusted Balance
Balance at Dec. 31, 2017	$ 188,054			$ (396)	$ 187,658	$ 172	$ 172	$ 107,256	$ 107,256	$ 106,599	$ (396)	$ 106,203	$ (11,118)	$ (11,118)	$ (14,855)			$ (14,855)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,836									9,836
Foreign currency translation adjustments	(6,914)														(6,914)
Change in fair value of derivative instrument, net of tax		$ 142	$ (63)													$ 142	$ (63)
Repurchases of common stock in the open market	(7,993)												(7,993)
Stock-based compensation expense	1,350							1,350
Shares withheld in exchange for tax withholding payments on stock-based compensation	(416)							(416)
Issuance of stock for employer contributions to retirement plan	2,960							(867)					3,827
Net issuances of stock pursuant to stock  compensation plans and other	9							(1,473)					1,482
Balance at Dec. 31, 2018	186,569					172		105,850		116,039			(13,802)		(21,690)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,189									15,189
Foreign currency translation adjustments	1,955														1,955
Stock-based compensation expense	2,617							2,617
Shares withheld in exchange for tax withholding payments on stock-based compensation	(278)							(278)
Issuance of stock for employer contributions to retirement plan	2,978							(2,251)					5,229
Net issuances of stock pursuant to stock  compensation plans and other	884							(3,619)					4,503
Balance at Dec. 31, 2019	209,914					172		102,319		131,228			(4,070)		(19,735)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,068									7,068
Foreign currency translation adjustments	1,412														1,412
Repurchases of common stock in the open market	(1,833)												(1,833)
Stock-based compensation expense	4,940							4,940
Shares withheld in exchange for tax withholding payments on stock-based compensation	(325)							(325)
Issuance of stock for employer contributions to retirement plan	3,037					1		(951)					3,987
Net issuances of stock pursuant to stock  compensation plans and other	(867)							(2,758)					1,891
Balance at Dec. 31, 2020	$ 223,346					$ 173		$ 103,225		$ 138,296			$ (25)		$ (18,323)