Stock-Based Compensation - Additional Information (Details) (USD $)	9 Months Ended			9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Two Thousand Twelve Incentive Plan	Sep. 30, 2014 Restricted Stock	Sep. 30, 2013 Restricted Stock	Sep. 30, 2014 Restricted Stock	Sep. 30, 2013 Restricted Stock	Sep. 30, 2014 Restricted Stock Stock Incentive Plan Twenty Twelve	Sep. 30, 2014 Restricted Stock Stock Incentive Plan Twenty Twelve	Sep. 30, 2014 Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	14,460,853										0
Shares transferred				1,030,673
Shares granted							2,374,998		45,500	2,374,998
Shares granted, weighted average grant date fair value							$ 16.80		$ 15.71	$ 16.80
Shares granted, vesting period							5 years
Compensation and benefits expense					$ 6,800,000	$ 5,700,000	$ 20,700,000	$ 16,600,000
Unrecognized compensation cost relating to unvested restricted stock					72,900,000		72,900,000
Unrecognized compensation cost relating to unvested restricted stock, recognition period (in years)							3 years 2 months 12 days
Stock option plans expiration period from date of grant											10 years
Number of unvested options	0		0
Stock option outstanding	58,560		126,821
Intrinsic value of stock options outstanding	0
Intrinsic value of stock options exercisable	0
Intrinsic values of options exercised	$ 132,000	$ 106,000