Equity-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Granted	0	0	0
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding at beginning of year	1,531,844	1,702,650	2,340,959
Shares, Granted	0	0	0
Shares, Exercised	(543,922)	(148,802)	(490,715)
Shares, Forfeited	0	(1,663)	(63,714)
Shares, Expired	(32,145)	(20,341)	(83,880)
Shares, Outstanding at end of period	955,777	1,531,844	1,702,650
Shares, Exercisable at end of period	955,777	1,527,814	1,589,096
Weighted-Average Exercise Price, Outstanding at beginning of year	$ 41.69	$ 40.43	$ 37.35
Weighted-Average Exercise Price, Granted	$ 0.00	$ 0.00	$ 0.00
Weighted-Average Exercise Price, Exercised	$ 39.54	$ 27.02	$ 26.63
Weighted-Average Exercise Price, Forfeited	$ 0.00	$ 36.36	$ 32.29
Weighted-Average Exercise Price, Expired	$ 45.81	$ 43.63	$ 40.76
Weighted-Average Exercise Price, Outstanding at end of year	$ 42.78	$ 41.69	$ 40.43
Weighted-Average Exercise Price, Exercisable at end of year	$ 42.78	$ 41.75	$ 40.84
Intrinsic value of exercised options	$ 4,300,000	$ 1,700,000	$ 6,400,000