CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]
Common stock, issued | Accounting Standards Update 2014-09 [Member]		102,567,129				29,145,976
Additional paid-in capital | Accounting Standards Update 2014-09 [Member]			$ 687,479
Retained earnings | Accounting Standards Update 2014-09 [Member]				$ 780,365
Accumulated other comprehensive income | Accounting Standards Update 2014-09 [Member]					$ 1,459
Total stockholders’ equity | Accounting Standards Update 2014-09 [Member]	$ 363,061	$ 10,257				$ (1,116,499)
Net income | Accounting Standards Update 2014-09 [Member]	40,521			40,521
Total other comprehensive income (loss) | Accounting Standards Update 2014-09 [Member]	1,401				1,401
Exercise of stock options (in shares) | Accounting Standards Update 2014-09 [Member]		66,567
Exercise of stock options, amount | Accounting Standards Update 2014-09 [Member]	2,410	$ 6	2,404
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares) | Accounting Standards Update 2014-09 [Member]		58,398
Issuance of restricted stock units and net share settlement related to withholding taxes, amount | Accounting Standards Update 2014-09 [Member]	(1,653)	$ 6	(1,659)
Repurchase of common stock (in shares) | Accounting Standards Update 2014-09 [Member]						839,159
Repurchase of common stock, amount | Accounting Standards Update 2014-09 [Member]	50,000					$ 50,000
Stock-based compensation | Accounting Standards Update 2014-09 [Member]	6,414		6,414
Net income	110,668
Net income | Accounting Standards Update 2014-09 [Member]	217,057
Total other comprehensive income (loss) | Accounting Standards Update 2014-09 [Member]	2,398
Common stock, issued | Accounting Standards Update 2014-09 [Member]		102,692,094				29,985,135
Additional paid-in capital | Accounting Standards Update 2014-09 [Member]			694,638
Retained earnings | Accounting Standards Update 2014-09 [Member]				820,886
Accumulated other comprehensive income | Accounting Standards Update 2014-09 [Member]					2,860
Total stockholders’ equity | Accounting Standards Update 2014-09 [Member]	362,154	$ 10,269				$ (1,166,499)
Net income | Accounting Standards Update 2014-09 [Member]	132,031			132,031
Total other comprehensive income (loss) | Accounting Standards Update 2014-09 [Member]	73				73
Exercise of stock options (in shares) | Accounting Standards Update 2014-09 [Member]		36,767
Exercise of stock options, amount | Accounting Standards Update 2014-09 [Member]	1,133	$ 4	1,129
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares) | Accounting Standards Update 2014-09 [Member]		47,058
Issuance of restricted stock units and net share settlement related to withholding taxes, amount | Accounting Standards Update 2014-09 [Member]	(1,789)	$ 5	(1,794)
Repurchase of common stock (in shares) | Accounting Standards Update 2014-09 [Member]						756,349
Repurchase of common stock, amount | Accounting Standards Update 2014-09 [Member]	50,000					$ 50,000
Stock-based compensation | Accounting Standards Update 2014-09 [Member]	5,455		5,455
Common stock, issued | Accounting Standards Update 2014-09 [Member]		102,775,919				30,741,484
Additional paid-in capital | Accounting Standards Update 2014-09 [Member]			699,428
Retained earnings | Accounting Standards Update 2014-09 [Member]				952,917
Accumulated other comprehensive income | Accounting Standards Update 2014-09 [Member]					2,933
Total stockholders’ equity | Accounting Standards Update 2014-09 [Member]	449,057	$ 10,278				$ (1,216,499)
Net income	37,835
Net income | Accounting Standards Update 2014-09 [Member]	44,505			44,505
Total other comprehensive income (loss) | Accounting Standards Update 2014-09 [Member]	924				924
Exercise of stock options (in shares) | Accounting Standards Update 2014-09 [Member]		112,972
Exercise of stock options, amount | Accounting Standards Update 2014-09 [Member]	3,826	$ 11	3,815
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares) | Accounting Standards Update 2014-09 [Member]		47,714
Issuance of restricted stock units and net share settlement related to withholding taxes, amount | Accounting Standards Update 2014-09 [Member]	(2,037)	$ 5	(2,042)
Repurchase of common stock (in shares) | Accounting Standards Update 2014-09 [Member]						649,479
Repurchase of common stock, amount | Accounting Standards Update 2014-09 [Member]	50,000					$ 50,000
Stock-based compensation | Accounting Standards Update 2014-09 [Member]	5,353		5,353
Common stock, issued | Accounting Standards Update 2014-09 [Member]		102,936,605				31,390,963
Additional paid-in capital | Accounting Standards Update 2014-09 [Member]			706,554
Retained earnings | Accounting Standards Update 2014-09 [Member]				997,422
Accumulated other comprehensive income | Accounting Standards Update 2014-09 [Member]					3,857
Total stockholders’ equity | Accounting Standards Update 2014-09 [Member]	$ 451,628	$ 10,294				$ (1,266,499)
Common stock, issued	103,130,300
Common stock, issued | Accounting Standards Update 2014-09 [Member]		103,130,300				31,943,599
Additional paid-in capital | Accounting Standards Update 2014-09 [Member]	$ 715,475		715,475
Retained earnings	305,208
Retained earnings | Accounting Standards Update 2014-09 [Member]	1,065,507			1,065,507
Accumulated other comprehensive income | Accounting Standards Update 2014-09 [Member]	1,388				1,388
Total stockholders’ equity | Accounting Standards Update 2014-09 [Member]	476,184	$ 10,313				$ (1,316,499)
Net income	38,066			38,066
Total other comprehensive income (loss)	(423)				(423)
Exercise of stock options (in shares)		90,009
Exercise of stock options, amount	3,711	$ 9	3,702
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares)		58,829
Issuance of restricted stock units and net share settlement related to withholding taxes, amount	(3,284)	$ 6	(3,290)
Repurchase of common stock (in shares)						473,376
Repurchase of common stock, amount	(50,000)					$ 50,000
Stock-based compensation	8,865		8,865
Net income	158,869
Total other comprehensive income (loss)	(159)
Common stock, issued		103,279,138				32,416,975
Additional paid-in capital			724,752
Retained earnings				1,103,573
Accumulated other comprehensive income					965
Total stockholders’ equity	473,119	$ 10,328				$ (1,366,499)
Net income	59,217			59,217
Total other comprehensive income (loss)	(895)				(895)
Exercise of stock options (in shares)		15,902
Exercise of stock options, amount	759	$ 2	757
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares)		100,643
Issuance of restricted stock units and net share settlement related to withholding taxes, amount	(6,341)	$ 10	(6,351)
Repurchase of common stock (in shares)						1,175,531
Repurchase of common stock, amount	(100,000)					$ 100,000
Stock-based compensation	6,335		6,335
Common stock, issued		103,395,683				33,592,506
Additional paid-in capital			725,493
Retained earnings				1,162,790
Accumulated other comprehensive income					70
Total stockholders’ equity	432,194	$ 10,340				$ (1,466,499)
Net income	61,587			61,587
Total other comprehensive income (loss)	1,159				1,159
Exercise of stock options (in shares)		39,303
Exercise of stock options, amount	1,448	$ 4	1,444
Issuance of restricted stock units and net share settlement related to withholding taxes (in shares)		43,604
Issuance of restricted stock units and net share settlement related to withholding taxes, amount	(2,357)	$ 4	(2,361)
Repurchase of common stock (in shares)						777,569
Repurchase of common stock, amount	(75,000)					$ 75,000
Stock-based compensation	$ 6,254		6,254
Common stock, issued	103,478,590	103,478,590				34,370,075
Additional paid-in capital	$ 730,830		$ 730,830
Retained earnings	1,224,377			$ 1,224,377
Accumulated other comprehensive income	1,229				$ 1,229
Total stockholders’ equity	$ 425,285	$ 10,348				$ (1,541,499)