Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock	Non - Controlling Interest
Beginning balance (in shares) at Dec. 31, 2016		35,699,819				2,071,710
Beginning balance at Dec. 31, 2016	$ 532,178	$ 36	$ 284,646	$ 382,722	$ (75,057)	$ (60,362)	$ 193
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued against stock-based compensation plans (in shares)		1,090,932
Stock issued against stock-based compensation plans	8,561	$ 1	8,560
Stock issued, business acquisition	0
Stock-based compensation	23,041		23,041
Acquisition of treasury stock (in shares)						(830,308)
Acquisition of treasury stock	(43,454)					$ (43,454)
Non-controlling interest	31						31
Other comprehensive income (loss)	29,347				29,347
Net income	48,888			48,888
Ending balance (in shares) at Dec. 31, 2017		36,790,751				2,902,018
Ending balance at Dec. 31, 2017	600,045	$ 37	322,246	427,064	(45,710)	$ (103,816)	224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued against stock-based compensation plans (in shares)		990,334
Stock issued against stock-based compensation plans	1,398	$ 1	1,397
Stock issued business acquisition (in shares)		69,459
Stock issued, business acquisition	4,080		4,080
Stock-based compensation	23,901		23,901
Acquisition of treasury stock (in shares)						(726,050)
Acquisition of treasury stock	(43,109)					$ (43,109)
Allocation of equity component related to the convertible senior notes, net of tax and issuance costs	12,555		12,555
Non-controlling interest	26						26
Other comprehensive income (loss)	(37,757)				(37,757)
Net income	$ 56,726			56,726
Ending balance (in shares) at Dec. 31, 2018	34,222,476	37,850,544				3,628,068
Ending balance at Dec. 31, 2018	$ 618,319	$ 38	364,179	484,244	(83,467)	$ (146,925)	250
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued against stock-based compensation plans (in shares)		630,110
Stock issued against stock-based compensation plans	987	$ 1	986
Stock issued, business acquisition	0
Stock-based compensation	26,070		26,070
Acquisition of treasury stock (in shares)						(667,345)
Acquisition of treasury stock	(41,364)					$ (41,364)
Allocation of equity component related to the convertible senior notes, net of tax and issuance costs	(13)		(13)
Purchase of non-controlling interest	(232)		18				(250)
Other comprehensive income (loss)	(1,425)				(1,425)
Net income	$ 67,659			67,659
Ending balance (in shares) at Dec. 31, 2019	34,185,213	38,480,654				4,295,413
Ending balance at Dec. 31, 2019	$ 670,001	$ 39	$ 391,240	$ 551,903	$ (84,892)	$ (188,289)	$ 0