Stock-Based Compensation - Additional Information (Detail) (USD $)	6 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2013 OptionPlan	Dec. 31, 2012	Jun. 30, 2013 Options and Restricted Stock	Jun. 30, 2013 Two Thousand Twelve Incentive Plan	Jun. 30, 2013 Stock Options	Jun. 30, 2013 Restricted Stock	Jun. 30, 2012 Restricted Stock	Jun. 30, 2013 Restricted Stock	Jun. 30, 2012 Restricted Stock	Jun. 30, 2013 Restricted Stock Stock Incentive Plan Twenty Twelve	Jun. 30, 2013 Restricted Stock Stock Incentive Plan Twenty Twelve
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant			16,782,051		11,453
Shares transferred				1,030,673
Shares granted	2,280,022									94,800	2,280,022
Shares granted, weighted average grant date fair value	$ 13.61									$ 13.31	$ 13.61
Shares granted, vesting period								5 years
Compensation and benefits expense						$ 5,400,000	$ 5,300,000	$ 11,000,000	$ 10,300,000
Unrecognized compensation cost relating to unvested restricted stock	66,500,000
Unrecognized compensation cost relating to unvested restricted stock, recognition period (in years)	3 years 6 months
Number of stock option plans	8
Stock option plans expiration period from date of grant	10 years
Stock option outstanding	341,128	2,641,344
Intrinsic value of stock options outstanding and exercisable	112,000
Intrinsic values of options exercised	$ 60,000