CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balances at Dec. 31, 2011	$ 283,061	$ 510	$ 429,734	$ (154,053)	$ 6,870
Balances (in shares) at Dec. 31, 2011		50,997
Increase (Decrease) in Stockholders' Equity
Stock-based award activity	(1,328)	5	(1,333)
Stock-based award activity (in shares)		556
Common stock repurchased and retired	(26,124)	(10)	(6,515)	(19,599)
Common stock repurchased and retired (in shares)		(1,012)
Common stock issued under employee stock purchase plan	3,448	2	3,446
Common stock issued under employee stock purchase plan (in shares)		155
Stock-based compensation	10,148		10,148
Tax benefit from exercise of stock options	3,118		3,118
Net income	14,736			14,736
Unrealized loss on marketable securities	(16)				(16)
Foreign currency translation adjustments	(537)				(537)
Balances at Jun. 30, 2012	286,506	507	438,598	(158,916)	6,317
Balances (in shares) at Jun. 30, 2012		50,696
Balances at Dec. 31, 2012	309,859	505	453,585	(154,261)	10,030
Balances (in shares) at Dec. 31, 2012		50,457
Increase (Decrease) in Stockholders' Equity
Stock-based award activity	9,706	15	9,691
Stock-based award activity (in shares)		1,606
Common stock issued under employee stock purchase plan	3,211	2	3,209
Common stock issued under employee stock purchase plan (in shares)		174
Stock-based compensation	26,621		26,621
Tax shortfall from exercise of stock options	(1,174)		(1,174)
Tax benefit from exercise of stock options	2,783		2,783
Cash dividends declared on common stock	(470,133)		(470,133)
Net income	7,990			7,990
Unrealized loss on marketable securities	(26)				(26)
Foreign currency translation adjustments	(3,650)				(3,650)
Balances at Jun. 30, 2013	$ (114,813)	$ 522	$ 24,582	$ (146,271)	$ 6,354
Balances (in shares) at Jun. 30, 2013		52,237