CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance (in shares) at Dec. 31, 2012		52,960,570
Balance at Dec. 31, 2012	$ 532,723	$ 530	$ 471,711	$ 61,687	$ (1,205)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		393,183
Exercise of common stock options	3,198	$ 3	3,195
Employee stock purchase plan (in shares)		203,200
Employee stock purchase plan	3,856	$ 2	3,854
Stock-based compensation expense	13,911
Vesting of restricted stock units and restricted stock awards (in shares)		369,572
Vesting of restricted stock units and restricted stock awards	(4,693)	$ 4	(4,697)
Tax deficiency from stock-based compensation	5,305		5,305
Fair value adjustment of derivatives, net of income tax	193				193
Translation adjustments	1,128				1,128
Net income (loss)	84,512			84,512
Balance (in shares) at Dec. 31, 2013		53,926,525
Balance at Dec. 31, 2013	640,133	$ 539	493,279	146,199	116
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		147,163
Exercise of common stock options	1,105	$ 1	1,104
Employee stock purchase plan (in shares)		207,805
Employee stock purchase plan	$ 5,253	$ 2	5,251
Stock repurchase and retirement (in shares)	(3,400,000)	(3,359,604)
Stock repurchase and retirement	$ (100,048)	$ (33)	31,194	68,821
Stock-based compensation expense	17,246
Vesting of restricted stock units and restricted stock awards (in shares)		464,804
Vesting of restricted stock units and restricted stock awards	(6,497)	$ 5	(6,502)
Tax deficiency from stock-based compensation	4,718		4,718
Fair value adjustment of derivatives, net of income tax	86				86
Translation adjustments	(4,772)				(4,772)
Net income (loss)	$ 77,184			77,184
Balance (in shares) at Dec. 31, 2014	51,386,693	51,386,693
Balance at Dec. 31, 2014	$ 634,408	$ 514	483,902	154,562	(4,570)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	329,502	329,502
Exercise of common stock options	$ 3,472	$ 3	3,469
Employee stock purchase plan (in shares)		204,401
Employee stock purchase plan	$ 5,293	$ 2	5,291
Stock repurchase and retirement (in shares)	(43,000)	(89,174)
Stock repurchase and retirement	$ (3,819)	$ (1)	1,173	2,645
Stock-based compensation expense	23,471
Vesting of restricted stock units and restricted stock awards (in shares)		398,850
Vesting of restricted stock units and restricted stock awards	(8,823)	$ 4	(8,827)
Tax deficiency from stock-based compensation	$ 6,551		6,551
Stock Issued During Period, Shares, Acquisitions	794,700	794,700
Stock Issued During Period, Value, Acquisitions	$ 30,183	$ 8	30,175
Fair value adjustment of derivatives, net of income tax	122				122
Translation adjustments	(3,714)				(3,714)
Net income (loss)	$ 97,650			97,650
Balance (in shares) at Dec. 31, 2015	53,024,972	53,024,972
Balance at Dec. 31, 2015	$ 784,794	$ 530	$ 542,859	$ 249,567	$ (8,162)