CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Employee Stock Options and Awards [Member]	Employee Stock Purchases [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Employee Stock Options and Awards [Member]	Additional Paid-In Capital [Member] Employee Stock Purchases [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2011	$ 364,529			$ 28	$ 158,646			$ 50	$ 205,805
Beginning Balance (in shares) at Dec. 31, 2011				28,065
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)				1,022
Issuance of common stock under employee stock option and stock award plans	18,200			0	18,200
Repurchase of common stock (in shares)				(676)
Repurchase of common stock	(20,467)			0	(20,467)
Issuance of common stock under employee stock purchase plan (in shares)				125
Issuance of common stock under employee stock purchase plan	3,752				3,752
Income tax benefits from employee stock plans	1,303				1,303
Stock-based compensation expense		13,092	1,142			13,092	1,142
Payment of dividends to stockholders	(5,755)								(5,755)
Unrealized actuarial loss on pension benefits, net of tax	(560)							(560)
Unrealized gain (loss) on marketable securities,	138							138
Translation adjustment	79							79
Net income (loss)	(34,404)								(34,404)
Ending Balance at Dec. 31, 2012	341,049			28	175,668			(293)	165,646
Ending Balance (in shares) at Dec. 31, 2012				28,536
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)				1,358
Issuance of common stock under employee stock option and stock award plans	26,269			2	26,267
Repurchase of common stock (in shares)				0
Repurchase of common stock	0			0	0
Issuance of common stock under employee stock purchase plan (in shares)				128
Issuance of common stock under employee stock purchase plan	3,971				3,971
Income tax benefits from employee stock plans	1,284				1,284
Stock-based compensation expense		15,275	1,195			15,275	1,195
Payment of dividends to stockholders	(9,446)								(9,446)
Unrealized actuarial loss on pension benefits, net of tax	(220)							(220)
Unrealized gain (loss) on marketable securities,	72							72
Translation adjustment	(29)							(29)
Net income (loss)	57,266								57,266
Ending Balance at Dec. 31, 2013	436,686			30	223,660			(470)	213,466
Ending Balance (in shares) at Dec. 31, 2013				30,022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)				697
Issuance of common stock under employee stock option and stock award plans	9,571			0	9,571
Repurchase of common stock (in shares)				(1,603)
Repurchase of common stock	(80,761)			(1)	(80,760)
Issuance of common stock under employee stock purchase plan (in shares)				92
Issuance of common stock under employee stock purchase plan	4,284				4,284
Income tax benefits from employee stock plans	815				815
Stock-based compensation expense		12,983	1,385			12,983	1,385
Payment of dividends to stockholders	(13,165)								(13,165)
Unrealized actuarial loss on pension benefits, net of tax	(460)							(460)
Unrealized gain (loss) on marketable securities,	(127)							(127)
Translation adjustment	(79)							(79)
Net income (loss)	59,544								59,544
Ending Balance at Dec. 31, 2014	$ 430,676			$ 29	$ 171,938			$ (1,136)	$ 259,845
Ending Balance (in shares) at Dec. 31, 2014				29,208