Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jun. 22, 2016	Jun. 21, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares grant of future awards	217,500,000		217,500,000
Number of limited partnership units exchangeable into shares	11,000,000		11,000,000		5,400,000
Notional value with post-termination pay-out amount	$ 133,200,000		$ 133,200,000		$ 30,400,000
Aggregate estimated fair value of limited partnership units	$ 22,100,000		$ 22,100,000		$ 11,300,000
Number of unvested limited partnership units with post-termination pay-out	14,600,000		14,600,000		3,300,000
Number of outstanding limited partnership units, unvested	9,800,000		9,800,000		1,600,000
Income allocated to limited partnership units	$ 24,400,000	$ 16,300,000	$ 40,000,000	$ 17,400,000
Restricted stock unit, Conversion description			Each RSU is settled in one share of Class A common stock upon completion of the vesting period.
Shares, Forfeited			59,000	44,000
Number of shares released the restrictions			4,400,000	2,400,000
Cash received per share upon conversion			$ 6.10
Deferred cash compensation expense recognized	3,500,000	6,300,000	$ 13,287,000	$ 17,615,000
Liability for deferred cash compensation awards	16,700,000		16,700,000
Deferred cash compensation expense not yet recognized	18,500,000		$ 18,500,000
Deferred cash compensation expense, expected period of recognition			11 months 1 day
Granted options			0
Exercised options			250,000
Compensation expense related to stock options	0	$ 0	$ 0	$ 0
Equity Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted options			0	0
Exercised options			250,000	84,000
Unrecognized compensation expense related to unvested stock options	$ 0		$ 0
Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Forfeited	43,657	43,624	59,317	218,747	270,422
Equity Plan [Member] | Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized to be delivered pursuant to awards granted						400,000,000	350,000,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	$ 1,200,000	$ 1,100,000	$ 4,000,000	$ 3,800,000
Awards granted			785,484,000	600,000
Aggregate estimated grant date fair values			$ 6,200,000	$ 4,900,000
Value of shares withheld			1,300,000	$ 1,300,000
Aggregate estimated grant date fair value of outstanding RSUs	10,400,000		10,400,000		$ 9,500,000
Unrecognized compensation expense related to unvested RSUs	$ 10,400,000		$ 10,400,000
Restricted shares outstanding	1,525,371		1,525,371		1,622,431
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period			2 years
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period			4 years
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares outstanding	14,700,000		14,700,000
Restricted Shares [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares saleable period			5 years
Restricted Shares [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares saleable period			10 years
Limited Partnership Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of limited partnership units granted exchangeability	4,600,000	3,800,000	11,100,000	10,900,000
Equity-based compensation expense	$ 34,300,000	$ 34,400,000	$ 92,700,000	$ 96,600,000
Aggregate estimated fair value of limited partnership units	25,500,000		25,500,000		$ 26,200,000
Compensation expense before income tax related to limited partnership units	$ 6,700,000	$ 3,800,000	$ 13,400,000	$ 11,100,000
Awards granted			30,587,554
Restricted shares outstanding	95,171,123		95,171,123		76,401,775
Limited Partnership Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period			3 years
Limited Partnership Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period			5 years
Limited Partnership Units [Member] | Restricted Shares [Member] | Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	$ 1,600,000
Restricted shares saleable period	4 years
Restricted shares granted	200,000