Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance at Dec. 31, 2014	$ 541,359	$ 58	$ 576,341	$ (106,231)	$ (333)	$ 71,524
Beginning balance (in shares) at Dec. 31, 2014		52,840		4,960
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	117,016					117,016
Other comprehensive gain (loss)	(1,104)				(1,104)
Cash dividends paid on common stock	(41,677)					(41,677)
Issuance of common stock in connection with exercise of stock options (in shares)		465
Issuance of common stock in connection with exercise of stock options	$ 8,995	$ 0	8,995
Issuance of common stock in connection with employee common stock purchase plan (in shares)	77	77
Issuance of common stock in connection with employee common stock purchase plan	$ 1,665		1,665
Issuance of restricted stock, net of shares cancelled (in shares)		350
Issuance of restricted stock, net of shares canceled	0	$ 0
Repurchases of common stock, shares exchanged (in shares)		(105)		(105)
Repurchases of common stock, shares exchanged	(4,047)			$ (4,047)
Repurchases of common stock (in shares)		(3,333)		(3,333)
Stock-based compensation expense	(119,235)			$ (119,235)
Tax effect from employee stock option plan	11,517		11,517
Tax effect from employee stock option plan	668		668
Ending balance at Dec. 31, 2015	515,157	$ 58	599,186	$ (229,513)	(1,437)	146,863
Ending balance (in shares) at Dec. 31, 2015		50,294		8,398
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	56,089					56,089
Other comprehensive gain (loss)	1,289				1,289
Cash dividends paid on common stock	(39,158)					(39,158)
Issuance of common stock in connection with exercise of stock options (in shares)		350
Issuance of common stock in connection with exercise of stock options	$ 6,285		6,285
Issuance of common stock in connection with employee common stock purchase plan (in shares)	89	89
Issuance of common stock in connection with employee common stock purchase plan	$ 1,998		1,998
Issuance of restricted stock, net of shares cancelled (in shares)		465
Issuance of restricted stock, net of shares canceled	1	$ 1
Repurchases of common stock, shares exchanged		$ (91)
Repurchases of common stock, shares exchanged (in shares)				(91)
Repurchases of common stock, shares exchanged	$ (2,900)			$ (2,900)
Repurchases of common stock (in shares)	(10,488)	(2,253)		(2,253)
Stock-based compensation expense	$ (67,701)			$ (67,701)
Tax effect from employee stock option plan	21,101		21,101
Fair value of partially vested equity awards assumed in connection with the acq. of DTS	13,124		13,124
Tax effect from employee stock option plan	2,500		2,500
Ending balance at Dec. 31, 2016	507,785	$ 59	644,194	$ (300,114)	(148)	163,794
Ending balance (in shares) at Dec. 31, 2016		48,854		10,742
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of ASU 2016-09	829					829
Net income (loss)	(56,558)					(56,558)
Other comprehensive gain (loss)	(155)				(155)
Cash dividends paid on common stock	(39,509)					(39,509)
Issuance of common stock in connection with exercise of stock options (in shares)		180
Issuance of common stock in connection with exercise of stock options	$ 4,872		4,872
Issuance of common stock in connection with employee common stock purchase plan (in shares)	164	164
Issuance of common stock in connection with employee common stock purchase plan	$ 4,132		4,132
Issuance of restricted stock, net of shares cancelled (in shares)		668
Issuance of restricted stock, net of shares canceled	1	$ 1
Repurchases of common stock, shares exchanged		$ (109)
Repurchases of common stock, shares exchanged (in shares)				(109)
Repurchases of common stock, shares exchanged	(3,944)			$ (3,944)
Repurchases of common stock (in shares)		(654)		(654)
Stock-based compensation expense	(15,339)			$ (15,339)
Tax effect from employee stock option plan	33,462		33,462
Ending balance at Dec. 31, 2017	$ 435,576	$ 60	$ 686,660	$ (319,397)	$ (303)	$ 68,556
Ending balance (in shares) at Dec. 31, 2017		49,103		11,505