Segment Reporting - Reportable Segments Financial Data (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fund level fee revenues
Fund management fees									$ 1,085.2	$ 1,166.3	$ 984.6
Performance fees
Realized									1,441.9	1,328.7	1,176.7
Unrealized									(617.0)	345.7	1,198.6
Total performance fees									824.9	1,674.4	2,375.3
Investment income (loss)
Realized									32.9	23.7	14.4
Unrealized									(17.7)	(30.9)	4.4
Total investment income (loss)									15.2	(7.2)	18.8
Other income									102.4	91.1	166.3
Total revenues	$ 715.8	$ 297.5	$ 856.1	$ 1,136.8	$ 839.1	$ 755.0	$ 1,138.8	$ 1,147.4	3,006.2	3,880.3	4,441.2
Performance fee related
Realized									650.5	590.7	539.2
Unrealized									(139.6)	282.2	644.5
Total compensation and benefits									1,521.1	2,005.9	2,244.1
General, administrative and other expenses									712.8	526.8	496.4
Interest									58.0	55.7	45.5
Total expenses	802.5	$ 795.3	$ 843.6	$ 1,027.0	928.7	$ 705.1	$ 1,042.6	$ 1,099.0	3,468.4	3,775.4	3,693.9
Segment assets	32,191.0				35,994.3				32,191.0	35,994.3	35,622.3
Corporate Private Equity
Performance fees
Total performance fees									698.2	1,340.2	1,907.4
Global Market Strategies
Performance fees
Total performance fees									(41.0)	81.7	208.2
Real Assets
Performance fees
Total performance fees									49.3	66.5	79.7
Investment Solutions
Performance fees
Total performance fees									118.4	186.0	180.0
Total Reportable Segments
Fund level fee revenues
Fund management fees									1,197.9	1,229.3	1,054.7
Portfolio advisory fees, net									15.4	20.1	25.9
Transaction fees, net									9.8	53.2	24.7
Total fund level fee revenues									1,223.1	1,302.6	1,105.3
Performance fees
Realized									1,434.8	1,323.7	1,128.6
Unrealized									(525.1)	384.2	1,164.7
Total performance fees									909.7	1,707.9	2,293.3
Investment income (loss)
Realized									(64.8)	(6.1)	10.6
Unrealized									42.4	(5.0)	(53.2)
Total investment income (loss)									(22.4)	(11.1)	(42.6)
Interest									4.8	2.2	1.8
Other income									17.2	20.4	11.1
Total revenues									2,132.4	3,022.0	3,368.9
Compensation and benefits
Direct base compensation									477.7	494.0	436.0
Indirect base compensation									172.1	188.5	152.8
Equity-based compensation									121.5	80.4	15.7
Performance fee related
Realized									646.3	590.9	454.1
Unrealized									(128.3)	309.6	647.8
Total compensation and benefits									1,289.3	1,663.4	1,706.4
General, administrative and other expenses									362.8	318.1	309.4
Depreciation and amortization expense									25.6	22.4	24.3
Interest									58.1	55.7	43.6
Total expenses									1,735.8	2,059.6	2,083.7
Economic Net Income (Loss)									396.6	962.4	1,285.2
Net Performance Fees									391.7	807.4	1,191.4
Reserve for litigation and contingencies									50.0	0.0	0.0
Investment Income (Loss)									(22.4)	(11.1)	(42.6)
Equity-based compensation									121.5	80.4	15.7
Fee Related Earnings									198.8	246.5	152.1
Realized Net Performance Fees									788.5	732.8	674.5
Realized Investment Income (Loss)									(64.8)	(6.1)	10.6
Distributable Earnings									922.5	973.2	837.2
Segment assets	6,114.0				7,397.4				6,114.0	7,397.4
Total Reportable Segments | Corporate Private Equity
Fund level fee revenues
Fund management fees									577.4	564.8	471.6
Portfolio advisory fees, net									14.3	18.4	23.2
Transaction fees, net									7.7	51.4	20.7
Total fund level fee revenues									599.4	634.6	515.5
Performance fees
Realized									1,209.5	1,156.3	914.5
Unrealized									(523.1)	197.2	959.1
Total performance fees									686.4	1,353.5	1,873.6
Investment income (loss)
Realized									23.3	17.7	15.8
Unrealized									(5.2)	13.9	10.4
Total investment income (loss)									18.1	31.6	26.2
Interest									1.5	1.4	0.9
Other income									9.8	9.4	5.6
Total revenues									1,315.2	2,030.5	2,421.8
Compensation and benefits
Direct base compensation									224.2	222.4	212.6
Indirect base compensation									91.5	101.8	95.0
Equity-based compensation									65.1	42.5	7.4
Performance fee related
Realized									540.9	512.5	401.7
Unrealized									(221.7)	97.1	446.2
Total compensation and benefits									700.0	976.3	1,162.9
General, administrative and other expenses									172.4	151.1	166.9
Depreciation and amortization expense									12.5	11.0	13.2
Interest									30.8	30.6	25.2
Total expenses									915.7	1,169.0	1,368.2
Economic Net Income (Loss)									399.5	861.5	1,053.6
Net Performance Fees									367.2	743.9	1,025.7
Reserve for litigation and contingencies									26.8
Investment Income (Loss)									18.1	31.6	26.2
Equity-based compensation									65.1	42.5	7.4
Fee Related Earnings									106.1	128.5	9.1
Realized Net Performance Fees									668.6	643.8	512.8
Realized Investment Income (Loss)									23.3	17.7	15.8
Distributable Earnings									798.0	790.0	537.7
Segment assets	3,127.0				4,065.1				3,127.0	4,065.1
Total Reportable Segments | Global Market Strategies
Fund level fee revenues
Fund management fees									210.7	259.3	275.2
Portfolio advisory fees, net									0.7	0.9	1.4
Transaction fees, net									0.0	0.2	0.1
Total fund level fee revenues									211.4	260.4	276.7
Performance fees
Realized									38.0	36.0	151.9
Unrealized									(63.1)	76.5	32.4
Total performance fees									(25.1)	112.5	184.3
Investment income (loss)
Realized									5.4	8.4	17.5
Unrealized									(15.7)	(3.6)	(1.5)
Total investment income (loss)									(10.3)	4.8	16.0
Interest									2.8	0.3	0.7
Other income									3.9	5.5	3.5
Total revenues									182.7	383.5	481.2
Compensation and benefits
Direct base compensation									101.2	110.6	99.6
Indirect base compensation									28.3	24.6	21.8
Equity-based compensation									19.0	13.9	3.0
Performance fee related
Realized									16.6	17.4	42.1
Unrealized									(27.7)	35.4	13.7
Total compensation and benefits									137.4	201.9	180.2
General, administrative and other expenses									69.8	52.9	60.9
Depreciation and amortization expense									5.0	4.0	4.5
Interest									10.8	9.7	7.9
Total expenses									223.0	268.5	253.5
Economic Net Income (Loss)									(40.3)	115.0	227.7
Net Performance Fees									(14.0)	59.7	128.5
Reserve for litigation and contingencies									9.0
Investment Income (Loss)									(10.3)	4.8	16.0
Equity-based compensation									19.0	13.9	3.0
Fee Related Earnings									12.0	64.4	86.2
Realized Net Performance Fees									21.4	18.6	109.8
Realized Investment Income (Loss)									5.4	8.4	17.5
Distributable Earnings									38.8	91.4	213.5
Segment assets	717.5				1,006.9				717.5	1,006.9
Total Reportable Segments | Real Assets
Fund level fee revenues
Fund management fees									255.9	223.8	188.9
Portfolio advisory fees, net									0.4	0.8	1.3
Transaction fees, net									2.1	1.6	3.9
Total fund level fee revenues									258.4	226.2	194.1
Performance fees
Realized									163.2	88.5	40.5
Unrealized									(42.5)	(39.5)	43.4
Total performance fees									120.7	49.0	83.9
Investment income (loss)
Realized									(93.6)	(32.2)	(22.7)
Unrealized									63.1	(15.7)	(62.3)
Total investment income (loss)									(30.5)	(47.9)	(85.0)
Interest									0.3	0.3	0.2
Other income									2.6	4.4	1.8
Total revenues									351.5	232.0	195.0
Compensation and benefits
Direct base compensation									70.0	75.2	70.2
Indirect base compensation									39.3	48.5	30.4
Equity-based compensation									25.0	19.2	4.6
Performance fee related
Realized									68.5	30.1	(4.0)
Unrealized									26.3	32.1	56.7
Total compensation and benefits									229.1	205.1	157.9
General, administrative and other expenses									74.6	72.2	58.4
Depreciation and amortization expense									4.3	3.6	4.3
Interest									10.6	9.9	8.2
Total expenses									318.6	290.8	228.8
Economic Net Income (Loss)									32.9	(58.8)	(33.8)
Net Performance Fees									25.9	(13.2)	31.2
Reserve for litigation and contingencies									9.2
Investment Income (Loss)									(30.5)	(47.9)	(85.0)
Equity-based compensation									25.0	19.2	4.6
Fee Related Earnings									71.7	21.5	24.6
Realized Net Performance Fees									94.7	58.4	44.5
Realized Investment Income (Loss)									(93.6)	(32.2)	(22.7)
Distributable Earnings									72.8	47.7	46.4
Segment assets	1,452.5				1,510.6				1,452.5	1,510.6
Total Reportable Segments | Investment Solutions
Fund level fee revenues
Fund management fees									153.9	181.4	119.0
Portfolio advisory fees, net									0.0	0.0	0.0
Transaction fees, net									0.0	0.0	0.0
Total fund level fee revenues									153.9	181.4	119.0
Performance fees
Realized									24.1	42.9	21.7
Unrealized									103.6	150.0	129.8
Total performance fees									127.7	192.9	151.5
Investment income (loss)
Realized									0.1	0.0	0.0
Unrealized									0.2	0.4	0.2
Total investment income (loss)									0.3	0.4	0.2
Interest									0.2	0.2	0.0
Other income									0.9	1.1	0.2
Total revenues									283.0	376.0	270.9
Compensation and benefits
Direct base compensation									82.3	85.8	53.6
Indirect base compensation									13.0	13.6	5.6
Equity-based compensation									12.4	4.8	0.7
Performance fee related
Realized									20.3	30.9	14.3
Unrealized									94.8	145.0	131.2
Total compensation and benefits									222.8	280.1	205.4
General, administrative and other expenses									46.0	41.9	23.2
Depreciation and amortization expense									3.8	3.8	2.3
Interest									5.9	5.5	2.3
Total expenses									278.5	331.3	233.2
Economic Net Income (Loss)									4.5	44.7	37.7
Net Performance Fees									12.6	17.0	6.0
Reserve for litigation and contingencies									5.0
Investment Income (Loss)									0.3	0.4	0.2
Equity-based compensation									12.4	4.8	0.7
Fee Related Earnings									9.0	32.1	32.2
Realized Net Performance Fees									3.8	12.0	7.4
Realized Investment Income (Loss)									0.1	0.0	0.0
Distributable Earnings									12.9	44.1	$ 39.6
Segment assets	$ 817.0				$ 814.8				$ 817.0	$ 814.8