Stockholders' Equity (details 2) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Dec. 31, 2010	Aug. 31, 2010	Dec. 31, 2010	Dec. 31, 2013	Dec. 31, 2011	Feb. 25, 2010
Share repurchase program
Number of shares authorized to be repurchased under 2001 plan				19,000,000
Additional number of shares authorized to be repurchased						12,500,000
Value of common stock to be repurchased from JP Morgan		$ 90.0
Prepayment to JP Morgan under Share repurchase agreement			90
Number of shares delivered by JP Morgan	4,800,000
Average price of shares delivered by JP Morgan (in dollars per share)					$ 18.88
Cumulative shares that have been repurchased in stock repurchase program				26,300,000
Cumulative value of shares that have been repurchased in stock repurchase program				$ 428.9
Remaining shares authorized to be repurchased				5,200,000