Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment [Member]	Common Stock	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings
Balance at Dec. 31, 2018			$ 48	$ 437,250	$ (2,588)	$ (233,676)	$ 152,650
Balance (in shares) at Dec. 31, 2018			31,771,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from the sales of stock through the Employee Stock Purchase Plan (in shares)			2,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan				44
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)			380,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions			$ 1	4,247
Purchases of treasury stock and buyback of shares for taxes (in shares)			(554,000)
Purchases of treasury stock and buyback of shares for taxes						(15,360)
Issuance of stock in conjunction with acquisition				0
Issuance of stock in conjunction with acquisition (in shares)			0
Foreign currency translation adjustment	$ 171				171
Net income	7,026						7,026
Balance at Mar. 31, 2019	349,813		$ 49	441,541	(2,417)	(249,036)	159,676
Balance (in shares) at Mar. 31, 2019			31,599,000
Balance at Dec. 31, 2019	$ 381,015	$ (315)	$ 49	455,465	(2,650)	(261,624)	189,775
Balance (in shares) at Dec. 31, 2019	31,686,991		31,687,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from the sales of stock through the Employee Stock Purchase Plan (in shares)			1,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan				40
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)			320,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions			$ 1	4,726
Equity component of convertible notes, net of tax	$ 15,547
Debt issuance costs of convertible notes, net of tax	523
Purchases of treasury stock and buyback of shares for taxes (in shares)			(114,000)
Purchases of treasury stock and buyback of shares for taxes						(4,835)
Issuance of stock in conjunction with acquisition				4,892
Issuance of stock in conjunction with acquisition (in shares)			167,000
Foreign currency translation adjustment	(974)				(974)
Net income	8,974						8,974
Balance at Mar. 31, 2020	$ 393,524		$ 50	$ 465,123	$ (3,624)	$ (266,459)	$ 198,434
Balance (in shares) at Mar. 31, 2020	32,061,167		32,061,000