Stock-Based Compensation - Narrative (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended									12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member] Repricing Option Program [Member]	Dec. 31, 2011 Stock Options [Member] Repricing Option Program [Member]	Nov. 30, 2003 Stock Options [Member] Repricing Option Program [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of stock-based compensation expense related to the modification of terms op options held					$ 1,500,000			$ 400,000
Proceeds from exercise of common stock options	1,711,000	3,484,000	2,680,000	1,700,000	3,500,000	2,700,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized				5,100,000						1,800,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition				3 years 7 months 17 days						3 years 6 months
Common Stock, Capital Shares Reserved for Future Issuance	6.9
Share Based Compensation, Repriced Options, Threshold									$ 1.00
Share Based Compensation, Repriced Options, Shares Exchanged							0.7
Share Based Compensation, Repriced Options, Options Issued After Wait Period							0.7
Share Based Compensation, Repriced Options, Average Exercise Price for Exchanged Options							$ 0.32
Share Based Compensation, Repriced Options, Effect on Share Based Compensation Expense								$ 500,000