Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)
Beginning Balance at Dec. 31, 2011	$ 1,106,202	$ 415	$ 383,978	$ 778,201	$ (56,392)
Beginning Balance (in shares) at Dec. 31, 2011		41,484,000
Net income (loss)	(36,986)			(36,986)
Other comprehensive income (loss):
Cumulative translation adjustment	15,023				15,023
Issuance of common stock in connection with:
Exercise of options, net of income tax expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014 (in shares)		328,000
Exercise of options, net of income tax expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014	7,043	4	7,039
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014 (in shares)		443,000
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014	(6,385)	4	(6,389)
Stock units issued under incentive compensation plan	3,079		3,079
Business combinations (in shares)		181,000
Business combinations	1,035	2	1,033
Reacquisition of equity component of convertible debt	(108)		(108)
Purchase and retirement of common stock (in shares)		(1,681,000)
Purchase and retirement of common stock	(50,032)	(17)	(50,015)
Share-based compensation	29,361		29,361
Ending Balance at Dec. 31, 2012	1,068,232	408	367,978	741,215	(41,369)
Ending 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 expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014 (in shares)		1,278,000
Exercise of options, net of income tax expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014	34,979	13	34,966
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014 (in shares)		369,000
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014	(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)		(1,957,000)
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	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 expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014 (in shares)	470,000	413,000
Exercise of options, net of income tax expense from share-based awards of $994 in 2012, $1,051 in 2013 and $1,451 in 2014	9,899	4	9,895
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014 (in shares)		242,000
Restricted share grants, less net settled shares of 178 in 2012, 178 in 2013 and 188 in 2014	(6,508)	3	(6,511)
Stock units issued under incentive compensation plan	1,674		1,674
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