Stockholders' Equity and Stock Based Compensation (Details Textual) (USD $)	1 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2012 Person	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stockholders Equity and Stock Based Compensation (Textual) [Abstract]
Percentage of fair market value of shares for calculation of exercise price SAR		not to be less than one hundred percent
Maximum term of SAR		10 years
Stockholders Equity and Stock Based Compensation Additional (Textual) [Abstract]
Shares outstanding options under the stock option plans		7,928,350	6,791,300	7,721,792	7,766,188
Shares available for future grant and issuance		2,938,928	4,793,640	1,648,700	410,873
Weighted average grant date fair value for stock option awards		$ 3.54	$ 4.00	$ 3.81
Minimum payroll deductions at base compensation under employee stock purchase plan	1.00%
Maximum payroll deductions at base compensation under employee stock purchase plan	10.00%
Maximum purchase limit of shares for each participant per offering period	500
Maximum purchase limit of shares for each participant annually	1,000
Maximum purchase limit of shares on the basis of fair market value on offering date, for each participant in any calendar year	$ 10,000
Purchase price of the common stock	lesser of 85% of the closing price on the first day of the applicable offering period (or most recently preceding trading day) or 85% of the closing price on the last day of the offering period
Maximum number of shares of common stock purchased for each offering period		100,000
Maximum number of shares of common stock purchased for each offering period annually		200,000
Number of individuals holding stock appreciation rights awards		1
Restricted stock and restricted stock unit [Member]
Stockholders Equity and Stock Based Compensation (Textual) [Abstract]
Intrinsic value of restricted stock and restricted stock unit awards		6,700,000
Weighted average grant date fair value for restricted stock and restricted stock unit awards		$ 6.05	$ 6.34	$ 6.30
Total fair value of shares vested		4,600,000	3,300,000	3,300,000
Employee Stock [Member]
Stockholders Equity and Stock Based Compensation (Textual) [Abstract]
Company recorded compensation expense approximately		300,000	300,000	0
Number of shares of common stock authorized and available for issuance under employee stock purchase program		1,265,311
Stock Appreciation Rights (SARs) [Member]
Stockholders Equity and Stock Based Compensation (Textual) [Abstract]
Company recorded compensation expense approximately		$ 100,000	$ 300,000	$ 100,000
Number of vested and outstanding stock appreciation rights		140,000
Weighted average exercise price of stock appreciation rights awards		$ 3.00