Share-Based Compensation (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Share-based compensation disclosures
Share Based Compensation expense	$ 10,700,000	$ 32,900,000
Liability related to awards	158,676,000		172,803,000
Restricted Stock Award | Employees and Director
Share-based compensation disclosures
Shares awarded during period	1,106,919	4,061,027
Aggregate value of restricted stock awards at date of grant	25,200,000	66,800,000
Fair value awards vested	22,400,000	35,500,000
Restricted Stock Award | Maximum | Employees and Director
Share-based compensation disclosures
Vesting period of shares	4 years
Restricted Stock Based on Performance Conditions | Executives
Share-based compensation disclosures
Shares awarded during period	362,311
Vesting period of shares	3 years
Liability related to awards	400,000
Restricted Stock Based on Market Conditions
Assumptions used to value grant date fair value
Risk free interest rate (as a percent	0.80%	0.41%
Expected volatility (as a percent)	40.00%	46.00%
Closing stock price (in dollars per share)	$ 18.19	$ 16.53
Expected term (in years)	2 years 11 months 19 days	2 years 9 months 25 days
Restricted Stock Based on Market Conditions | Executives
Share-based compensation disclosures
Shares awarded during period	395,550	353,933
Aggregate value of restricted stock awards at date of grant	4,500,000	3,700,000
Stock options | Employees and Director
Share-based compensation disclosures
Total intrinsic value of stock options exercised	6,000,000	700,000
Total fair value of option vested during the period	$ 1,500,000	$ 3,800,000