Stockholders' Equity and Stock-Based Compensation (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Additional information related to the Company's stock options
Number of Shares, Beginning Balance	6,791,300	7,721,792	7,766,188
Available for Grant, Options Granted	(1,544,000)	(1,559,400)	(1,249,900)
Weighted Average Exercise Price, Option granted	$ 6.05
Weighted average grant date fair value, Options granted	$ 3.54	$ 4.00	$ 3.81
Exercise of stock options, shares	(194,410)	(2,145,792)	(323,610)
Weighted Average Exercise Price, Options exercised	$ 4.15
Number of Shares, Options cancelled	(93,375)
Weighted Average Exercise Price, Options cancelled	$ 5.98
Number of Shares, Options forfeited	(119,165)
Weighted Average Exercise Price, Options forfeited	$ 10.29
Number of Shares, Ending Balance	7,928,350	6,791,300	7,721,792
Weighted average exercise price, beginning balance	$ 7.42
Weighted Average Exercise Price, Ending Balance	$ 7.19	$ 7.42
Weighted Average Remaining Contract Life, Beginning Balance	6 years 10 months 24 days	7 years 1 month 6 days
Weighted Average Remaining Contract Life, Ending Balance	6 years 10 months 24 days	7 years 1 month 6 days
Aggregate Intrinsic Value, Ending Balance	$ 6,510,000
Number of Shares, Options exercisable and vested	4,591,238
Weighted Average Exercise Price, Options exercisable and vested	$ 7.98
Weighted Average Remaining Contractual Life in Years, Options exercisable and vested	5 years 4 months 24 days
Aggregate Intrinsic Value, Options exercisable and vested	4,664,000
Total intrinsic value of options exercised	600,000	13,300,000	900,000
Cash received from option exercises	$ 800,000	$ 13,100,000	$ 1,100,000