Incentive Plans - Summary of Fund Interests and Other Similar Deferred Compensation Arrangements (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangements [Abstract]
Prepaid Compensation Asset, Beginning Balance	$ 47,445	$ 17,783
Prepaid Compensation Asset, Granted	72,217	64,679
Prepaid Compensation Asset, Settled
Prepaid Compensation Asset, Forfeited	(1,075)	(1,603)
Prepaid Compensation Asset, Amortization	(58,023)	(33,476)
Prepaid Compensation Asset, Increase in fair value of underlying investments
Prepaid Compensation Asset, Adjustment for estimated forfeitures
Prepaid Compensation Asset, Other	(131)	62
Prepaid Compensation Asset, Ending Balance	60,433	47,445
Compensation Liability, Beginning Balance	97,593	29,900
Compensation Liability, Granted	72,217	64,679
Compensation Liability, Settled	(24,006)	(10,646)
Compensation Liability, Forfeited	(1,544)	(1,711)
Compensation Liability, Amortization
Compensation Liability, Increase in fair value of underlying investments	14,099	7,557
Compensation Liability, Adjustment for estimated forfeitures	4,643	7,841
Compensation Liability, Other	(580)	(27)
Compensation Liability, Ending Balance	$ 162,422	$ 97,593