Stock-Based Compensation (Details) (USD $)	12 Months Ended						12 Months Ended		12 Months Ended
	Dec. 31, 2012 Employee stock purchase plan Item	Dec. 31, 2012 Stock options	Dec. 31, 2010 RSUs Performance-contingent Senior management Employee	Dec. 31, 2012 RSAs Performance-contingent Senior management Employee Item	Dec. 31, 2011 RSAs Performance-contingent Senior management Employee	Dec. 31, 2011 RSAs Performance-contingent Non-executive officer Non-employee	Dec. 31, 2012 2012 Employee Incentive Plan	May 31, 2012 2012 Employee Incentive Plan	Dec. 31, 2011 Prior Plans
Information related to stock-based compensation
Shares of common stock approved and authorized for issuance	2,025,000		210,000	44,500	1,290,000	25,000		6,500,000
Additional number of shares of common stock approved and authorized for issuance									12,667,411
Reduction in number of shares 2012 plan reserve for each stock option and SAR granted							1
Reduction in number of shares 2012 plan reserve for each stock award other than option and SAR granted							1.45
Shares remaining available for issuance	423,575						5,023,370
Maximum term for stock options		10 years
Vesting term for stock option		4 years
Percentage of stock options to be vested at end of year one		25.00%
Percentage of stock options to be vested monthly over remaining three years		75.00%
Purchase price as a percentage of fair market value of stock	85.00%
Consecutive and overlapping offering periods	24 months
Number of offering periods	4
Duration of purchase period	6 months
Maximum contributions as a percentage of employee's eligible compensation	15.00%
Stock issued during period (in shares)	1,601,425
Cumulative average sale price per share as of the period end (in dollars per share)	$ 10.75
Number of possible performance conditions, achievement of which not probable				1
Number of possible performance conditions				3