Share-Based and Other Deferred Compensation - Additional information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			9 Months Ended				3 Months Ended	9 Months Ended	3 Months Ended			9 Months Ended		0 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]	Sep. 30, 2013 Employee Loans [Member]	Sep. 30, 2013 Employee Loans [Member]	Sep. 30, 2013 Deferred Cash Program [Member]	Sep. 30, 2012 Deferred Cash Program [Member]	Mar. 31, 2011 Deferred Cash Program [Member]	Sep. 30, 2013 Deferred Cash Program [Member]	Sep. 30, 2012 Deferred Cash Program [Member]	Jul. 23, 2013 Long Term Incentive Plan [Member]	Sep. 30, 2013 Long Term Incentive Plan [Member]	Sep. 30, 2013 Long Term Incentive Plan [Member]	Oct. 23, 2013 Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service based awards granted (in shares)				2,237,000
Service based awards, grant date fair value (in dollars per share)						$ 26.60	$ 50.33
Service based awards vested (in shares)				2,083,000
Service based awards forfeited (in shares)				58,000
Deferred compensation, vesting period (in years)								P1Y				P4Y
Compensation expense related to deferred compensation program								$ 1,558	$ 4,442	$ 949	$ 1,053		$ 2,778	$ 3,318		$ 630	$ 630
Compensation expense related to service-based awards	19,496		15,654	60,723	46,353
Compensation expense related to amortization of LP units	4,820		5,464	15,243	15,293
Compensation expense related to acquisition related awards	1,867		4,457	9,093	15,089
Compensation expense related to deferred cash consideration	1,095		2,036	3,359	6,657
Additional shares to be granted under stock incentive plan		5,000,000
Long Term Incentive Plan Performance Period															4 years
Long Term Incentive Plan Payment Period															2 years
Deferred Compensation Arrangement with Individual, Maximum Contractual Term								P5Y
Deferred Compensation Arrangement with Individual, Recorded Liability								$ 10,723	$ 10,723
LP Units, Transfer Restrictions Released (in LP units)																		1,267,000
Restricted Class A Shares, Transfer Restrictions Released (in shares)																		610,000