Consolidated Statements of Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Treasury Stock	Non - Controlling Interest
Beginning balance (in shares) at Dec. 31, 2014			34,203,352				(1,297,885)
Beginning balance at Dec. 31, 2014		$ 419,158	$ 34	$ 233,173	$ 269,424	$ (55,509)	$ (27,964)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued on exercise/vesting of equity awards (in shares)			577,849
Stock issued on exercise/vesting of equity awards		3,375	$ 1	3,374
Stock based compensation		16,047		16,047
Excess tax benefit from stock based compensation		1,458		1,458
Acquisition of treasury stock (in shares)							(392,093)
Acquisition of treasury stock		(14,195)					$ (14,195)
Non-controlling interest		179						179
Other comprehensive income		(11,816)				(11,816)
Net income		51,565			51,565
Ending balance (in shares) at Dec. 31, 2015			34,781,201				(1,689,978)
Ending balance at Dec. 31, 2015		465,771	$ 35	254,052	320,989	(67,325)	$ (42,159)	179
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued on exercise/vesting of equity awards (in shares)			918,618
Stock issued on exercise/vesting of equity awards		6,499	$ 1	6,498
Stock based compensation		19,770		19,770
Excess tax benefit from stock based compensation		4,326		4,326
Acquisition of treasury stock (in shares)							(381,732)
Acquisition of treasury stock		(18,203)					$ (18,203)
Non-controlling interest		14						14
Other comprehensive income		(7,732)				(7,732)
Net income		$ 61,733			61,733
Ending balance (in shares) at Dec. 31, 2016		33,628,109	35,699,819				(2,071,710)
Ending balance at Dec. 31, 2016		$ 532,178	$ 36	284,646	382,722	(75,057)	$ (60,362)	193
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact on adoption of ASU 2016-09	[1]	1,453		5,999	(4,546)
Adjusted equity balance		533,631	$ 36	290,645	378,176	(75,057)	$ (60,362)	193
Stock issued on exercise/vesting of equity awards (in shares)			1,090,932
Stock issued on exercise/vesting of equity awards		8,561	$ 1	8,560
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		29,347				29,347
Net income		$ 48,888			48,888
Ending balance (in shares) at Dec. 31, 2017		33,888,733	36,790,751				(2,902,018)
Ending balance at Dec. 31, 2017		$ 600,045	$ 37	$ 322,246	$ 427,064	$ (45,710)	$ (103,816)	$ 224

[1] Refer note 2(o) to consolidated financial statements for details.