Equity-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock that may be issued for awards pursuant to the 2011 plan	11,750,000
Aggregate number of shares of common stock that may be issued pursuant to the terms of the 2007 plan	4,000,000
Restricted Stock and Restricted Stock Units to be Settled in Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares	1,500,000	1,300,000	1,100,000
Granted, Weighted Average Grant Date Fair Value (Per share)	$ 29.37	$ 21.84	$ 21.38
Vesting period for restricted stock and restricted stock units	3 years
Vested, shares	1,200,000	900,000	800,000
Fair value of restricted stock, vested	$ 32.8	$ 22.3	$ 18.9
Unrecognized compensation cost, related to unvested restricted stock, total	28.9
Expected weighted average period to recognize compensation cost on restricted stock (in years)	1 year 8 months 5 days
Restricted Stock and Restricted Stock Units to be Settled in Common Stock [Member] | Former Executive Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost associated with the accelerated vesting of restricted stock and RSUs	4.3
Restricted Stock Units to be Settled in Cash [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for restricted stock and restricted stock units	3 years
Number of common stock shares that may be received by RSU holder	1
Compensation expense related to Restricted Stock Units to be settled in cash	3.1	2.0	1.3
Payment to settle liabilities under compensation plan	1.8	1.7	1.0
Liabilities under Compensation Plan	$ 2.1	$ 0.8