Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2013	38,291
Balance at Dec. 31, 2013	$ 234,201	$ 82,938	$ 6,260	$ 323,399
Net income		35,495		35,495
Other comprehensive loss			(449)	(449)
Dividends and dividend equivalents declared		(18,319)		$ (18,319)
Exercise of stock options (in shares)	742			742
Exercise of stock options	$ 11,941			$ 11,941
Release of restricted stock units (in shares)	772
Repurchase of common shares (in shares)	(1,051)
Repurchase of common shares	$ (41,198)			(41,198)
Shares issued under the employee stock purchase plan (in shares)	78
Shares issued under the employee stock purchase plan	$ 2,078			2,078
Stock-based compensation expense	33,459			33,459
Tax benefits from equity awards	$ 19			19
Balance (in shares) at Dec. 31, 2014	38,832
Balance at Dec. 31, 2014	$ 240,500	100,114	5,811	346,425
Net income		35,172		35,172
Other comprehensive loss			(4,345)	(4,345)
Dividends and dividend equivalents declared		(33,999)		$ (33,999)
Exercise of stock options (in shares)	498			498
Exercise of stock options	$ 7,744			$ 7,744
Release of restricted stock units (in shares)	948
Repurchase of common shares (in shares)	(645)
Repurchase of common shares	$ (32,286)			(32,286)
Shares issued under the employee stock purchase plan (in shares)	56
Shares issued under the employee stock purchase plan	$ 2,227			2,227
Stock-based compensation expense	41,650			41,650
Tax benefits from equity awards	$ 5,928			$ 5,928
Balance (in shares) at Dec. 31, 2015	39,689			39,689
Balance at Dec. 31, 2015	$ 265,763	101,287	1,466	$ 368,516
Net income		52,720		52,720
Other comprehensive loss			(5,681)	(5,681)
Dividends and dividend equivalents declared		(34,645)		$ (34,645)
Exercise of stock options (in shares)	76			76
Exercise of stock options	$ 1,344			$ 1,344
Release of restricted stock units (in shares)	975
Shares issued under the employee stock purchase plan (in shares)	53
Shares issued under the employee stock purchase plan	$ 2,463			2,463
Stock-based compensation expense	44,934			44,934
Tax benefits from equity awards	$ 1,465			$ 1,465
Balance (in shares) at Dec. 31, 2016	40,793			40,793
Balance at Dec. 31, 2016	$ 315,969	$ 119,362	$ (4,215)	$ 431,116