Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)
Beginning Balance at Dec. 31, 2012	$ 1,068,232	$ 408	$ 367,978	$ 741,215	$ (41,369)
Beginning Balance (in shares) at Dec. 31, 2012		40,755,000
Net income (loss)	(10,594)			(10,594)
Other comprehensive income (loss):
Cumulative translation adjustment	(9,720)				(9,720)
Issuance of common stock in connection with:
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015 (in shares)		1,278,000
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015	34,979	$ 13	34,966
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015 (in shares)		369,000
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015	(6,337)	$ 3	(6,340)
Stock units issued under incentive compensation plan	3,005		3,005
Business combinations (in shares)		81,000
Business combinations	$ (1,305)	$ 1	(1,306)
Purchase and retirement of common stock (in shares)	(1,956,900)	(1,957,000)
Purchase and retirement of common stock	$ (71,130)	$ (20)	(71,110)
Share-based compensation	35,129		35,129
Ending Balance at Dec. 31, 2013	1,042,259	$ 405	362,322	730,621	(51,089)
Ending Balance (in shares) at Dec. 31, 2013		40,526,000
Net income (loss)	58,807			58,807
Other comprehensive income (loss):
Cumulative translation adjustment	(29,179)				(29,179)
Issuance of common stock in connection with:
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015 (in shares)		413,000
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015	9,899	$ 4	9,895
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015 (in shares)		242,000
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015	(6,508)	$ 3	(6,511)
Stock units issued under incentive compensation plan	$ 1,674		1,674
Purchase and retirement of common stock (in shares)	0
Non-employee vesting of stock options	$ 2,951		2,951
Share-based compensation	22,843		22,843
Ending Balance at Dec. 31, 2014	$ 1,102,746	$ 412	393,174	789,428	(80,268)
Ending Balance (in shares) at Dec. 31, 2014	41,181,000	41,181,000
Net income (loss)	$ 66,053			66,053
Other comprehensive income (loss):
Cumulative translation adjustment	$ (28,727)				(28,727)
Issuance of common stock in connection with:
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015 (in shares)	763,000	713,000
Exercise of options, net of income tax benefit from share-based awards of $1,051 in 2013, $1,451 in 2014, and $2,050 in 2015	$ 19,026	$ 7	19,019
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015 (in shares)		105,000
Restricted share grants, less net settled shares of 178 in 2013, 188 in 2014 and 116 in 2015	(4,371)	$ 1	(4,372)
Stock units issued under incentive compensation plan	$ 2,124		2,124
Purchase and retirement of common stock (in shares)	(764,545)	(765,000)
Purchase and retirement of common stock	$ (26,532)	$ (8)	(26,524)
Share-based compensation	17,284		17,284
Ending Balance at Dec. 31, 2015	$ 1,147,603	$ 412	$ 400,705	$ 855,481	$ (108,995)
Ending Balance (in shares) at Dec. 31, 2015	41,234,000	41,234,000