Stock-Based Compensation - Narrative (Details) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended			6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Stock Options	Jun. 30, 2014 Restricted Stock Units (RSUs)	Jun. 30, 2014 LTIP	Jun. 30, 2013 LTIP	Jun. 30, 2014 LTIP	Jun. 30, 2013 LTIP	Dec. 31, 2013 LTIP	Jun. 30, 2014 LTIP Minimum	Jun. 30, 2014 LTIP Maximum	Jun. 30, 2013 Board of Directors Restricted Stock Units (RSUs)	Jun. 30, 2013 Board of Directors Restricted Stock Units (RSUs)	May 17, 2011 2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)																	1,500,000
Total compensation cost not yet recognized						$ 5,100,000	$ 12,200,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition (in years)						1 year 6 months 28 days	1 year 6 months 22 days
Share-based compensation expense	3,000,000	2,100,000	6,000,000	5,800,000				600,000	(600,000)	500,000	(400,000)				0	300,000
Accrued employee compensation and benefits	$ 14,404,000		$ 14,404,000		$ 24,956,000			$ 2,000,000		$ 2,000,000		$ 2,800,000
Award vesting period (in years)										3 years
Multiplier for target award based on total shareholder return on common stock (percent)													0.00%	200.00%