Stockholders' Equity and Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Transactions under the stock option plans
Weighted average exercise price, minimum, beginning balance	$ 2.49	$ 2.49	$ 1.07
Weighted average exercise price, maximum, beginning balance	$ 16.39	$ 16.39	$ 16.39	$ 16.39
Number of Shares, Beginning Balance	6,791,300	7,721,792	7,766,188
Vested, beginning balance	3,844,538	5,389,408	5,042,682
Available for Grant, beginning balance	4,793,640	1,648,700	410,873
Increase in shares authorized		5,000,000	2,500,000
Granted minimum	$ 5.96	$ 5.81	$ 3.42
Granted maximum	$ 7.16	$ 10.09	$ 7.19
Available for Grant, Options Granted	(1,544,000)	(1,559,400)	(1,249,900)
Vested	1,060,275	851,222	1,370,897
Exercised, minimum	$ 2.49	$ 2.49	$ 1.07
Exercised maximum	$ 7.76	$ 11.51	$ 7.31
Exercise of stock options, shares	194,410	2,145,792	323,610
Cancelled/forfeited, minimum	$ 2.49	$ 3.00	$ 1.07
Cancelled/forfeited, maximum	$ 15.43	$ 15.43	$ 16.12
Cancelled/forfeited, Outstanding	(212,540)	(344,100)	(970,686)
Cancelled/forfeited, Vested	(119,165)	(250,300)	(700,561)
Cancelled/forfeited, Available for Grant	127,125	262,513	674,363
Restricted stock granted out of option plans	(667,000)	(651,661)	(762,680)
Restricted stock forfeited or cancelled for employee minimum income taxes and returned to the plans	229,163	93,488	76,044
Weighted average exercise price, minimum, Ending balance	$ 2.80	$ 2.49	$ 2.49
Number of Shares, Ending Balance	7,928,350	6,791,300	7,721,792
Vested, ending balance	4,591,238	3,844,538	5,389,408
Available for Grant, ending balance	2,938,928	4,793,640	1,648,700