Segment Reporting - Reportable Segments Financial Data (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fund level fee revenues
Fund management fees	$ 255.1	$ 278.3	$ 817.1	$ 830.1
Performance fees
Realized	383.4	329.2	905.1	1,251.0
Unrealized	(168.7)	(575.8)	(334.3)	(629.7)
Total performance fees	214.7	(246.6)	570.8	621.3
Investment income (loss)
Realized	40.7	12.5	92.2	24.2
Unrealized	29.8	(22.0)	34.0	(17.7)
Total investment income (loss)	70.5	(9.5)	126.2	6.5
Other income	3.0	40.4	6.2	88.0
Total revenues	607.3	297.5	1,698.4	2,290.4
Performance fee related
Realized	189.0	155.2	423.0	561.7
Unrealized	(78.1)	(228.1)	(146.1)	(146.2)
Total compensation and benefits	346.6	177.4	1,013.2	1,178.7
General, administrative, and other indirect expenses	188.9	289.6	362.6	539.2
Interest expense	15.6	14.5	46.3	43.6
Total expenses	661.8	795.3	1,668.1	2,665.9
Net Performance Fees	103.8	(173.7)	293.9	205.8
Segment assets	9,503.6		9,503.6		$ 32,181.6
Corporate Private Equity
Performance fees
Total performance fees	186.5	(257.8)	283.0	522.4
Global Market Strategies
Performance fees
Total performance fees	17.8	(52.3)	26.8	(29.9)
Real Assets
Performance fees
Total performance fees	(19.1)	32.1	198.6	3.3
Investment Solutions
Performance fees
Total performance fees	29.5	31.4	62.4	125.5
Operating Segments
Fund level fee revenues
Fund management fees	260.4	311.9	820.0	919.3
Portfolio advisory fees, net	3.8	3.0	12.8	12.3
Transaction fees, net	1.4	1.0	24.3	4.1
Total fund level fee revenues	265.6	315.9	857.1	935.7
Performance fees
Realized	380.9	333.1	919.2	1,251.8
Unrealized	(125.9)	(554.2)	(305.9)	(539.3)
Total performance fees	255.0	(221.1)	613.3	712.5
Investment income (loss)
Realized	11.1	9.2	27.9	(66.7)
Unrealized	2.2	(15.5)	7.9	43.4
Total investment income (loss)	13.3	(6.3)	35.8	(23.3)
Interest income	2.5	0.1	8.0	1.4
Other income	3.1	4.9	8.9	15.2
Total revenues	539.5	93.5	1,523.1	1,641.5
Compensation and benefits
Direct base compensation	107.1	121.7	337.4	361.6
Indirect base compensation	36.9	42.8	115.1	133.8
Equity-based compensation	32.9	30.8	95.2	91.0
Performance fee related
Realized	194.6	155.9	429.5	563.5
Unrealized	(81.9)	(228.4)	(149.2)	(133.4)
Total compensation and benefits	289.6	122.8	828.0	1,016.5
General, administrative, and other indirect expenses	173.6	78.1	326.7	238.8
Depreciation and amortization expense	7.2	6.6	21.8	18.8
Interest expense	15.6	14.4	46.3	43.5
Total expenses	486.0	221.9	1,222.8	1,317.6
Economic Net Income (Loss)	53.5	(128.4)	300.3	323.9
Net Performance Fees	142.3	(148.6)	333.0	282.4
Investment Income (Loss)	13.3	(6.3)	35.8	(23.3)
Equity-based compensation	32.9	30.8	95.2	91.0
Reserve for Litigation and Contingencies	100.0	0.0	100.0	0.0
Fee Related Earnings	30.8	57.3	126.7	155.8
Realized Net Performance Fees	186.3	177.2	489.7	688.3
Realized Investment Income (Loss)	11.1	9.2	27.9	(66.7)
Distributable Earnings	228.2	243.7	644.3	777.4
Segment assets	6,031.7		6,031.7
Operating Segments | Corporate Private Equity
Fund level fee revenues
Fund management fees	122.9	152.5	376.9	443.5
Portfolio advisory fees, net	2.9	2.8	11.2	11.3
Transaction fees, net	1.4	0.9	24.3	3.7
Total fund level fee revenues	127.2	156.2	412.4	458.5
Performance fees
Realized	311.1	258.6	775.2	1,101.1
Unrealized	(124.2)	(513.9)	(496.2)	(583.0)
Total performance fees	186.9	(255.3)	279.0	518.1
Investment income (loss)
Realized	24.1	11.0	46.6	22.0
Unrealized	(9.6)	(12.7)	(12.7)	(4.6)
Total investment income (loss)	14.5	(1.7)	33.9	17.4
Interest income	0.9	0.4	2.7	0.9
Other income	1.3	2.7	4.0	8.1
Total revenues	330.8	(97.7)	732.0	1,003.0
Compensation and benefits
Direct base compensation	52.7	59.1	165.8	169.3
Indirect base compensation	17.8	23.3	55.6	71.1
Equity-based compensation	19.8	17.0	56.0	49.6
Performance fee related
Realized	143.5	120.6	345.4	494.8
Unrealized	(57.8)	(235.0)	(219.9)	(256.8)
Total compensation and benefits	176.0	(15.0)	402.9	528.0
General, administrative, and other indirect expenses	81.4	36.4	144.3	105.9
Depreciation and amortization expense	3.4	3.3	10.2	9.0
Interest expense	7.0	7.8	21.2	23.1
Total expenses	267.8	32.5	578.6	666.0
Economic Net Income (Loss)	63.0	(130.2)	153.4	337.0
Net Performance Fees	101.2	(140.9)	153.5	280.1
Investment Income (Loss)	14.5	(1.7)	33.9	17.4
Equity-based compensation	19.8	17.0	56.0	49.6
Reserve for Litigation and Contingencies	49.8		49.8
Fee Related Earnings	16.9	29.4	71.8	89.1
Realized Net Performance Fees	167.6	138.0	429.8	606.3
Realized Investment Income (Loss)	24.1	11.0	46.6	22.0
Distributable Earnings	208.6	178.4	548.2	717.4
Segment assets	2,778.8		2,778.8
Operating Segments | Global Market Strategies
Fund level fee revenues
Fund management fees	44.1	52.3	147.4	162.6
Portfolio advisory fees, net	0.1	0.1	0.7	0.6
Transaction fees, net	0.0	0.0	0.0	0.0
Total fund level fee revenues	44.2	52.4	148.1	163.2
Performance fees
Realized	14.3	11.8	21.5	25.0
Unrealized	3.1	(62.4)	4.6	(40.1)
Total performance fees	17.4	(50.6)	26.1	(15.1)
Investment income (loss)
Realized	1.1	3.1	2.7	5.9
Unrealized	7.1	(5.0)	14.9	(10.7)
Total investment income (loss)	8.2	(1.9)	17.6	(4.8)
Interest income	1.1	(0.4)	3.7	0.2
Other income	1.2	1.1	3.5	3.7
Total revenues	72.1	0.6	199.0	147.2
Compensation and benefits
Direct base compensation	20.9	22.4	66.3	75.3
Indirect base compensation	7.5	6.9	22.7	22.1
Equity-based compensation	4.4	5.0	13.8	14.5
Performance fee related
Realized	6.6	5.4	8.1	11.8
Unrealized	1.3	(28.6)	2.2	(18.6)
Total compensation and benefits	40.7	11.1	113.1	105.1
General, administrative, and other indirect expenses	37.7	14.0	77.1	49.1
Depreciation and amortization expense	1.5	1.3	4.6	3.7
Interest expense	3.0	2.6	8.5	8.1
Total expenses	82.9	29.0	203.3	166.0
Economic Net Income (Loss)	(10.8)	(28.4)	(4.3)	(18.8)
Net Performance Fees	9.5	(27.4)	15.8	(8.3)
Investment Income (Loss)	8.2	(1.9)	17.6	(4.8)
Equity-based compensation	4.4	5.0	13.8	14.5
Reserve for Litigation and Contingencies	19.0		19.0
Fee Related Earnings	(5.1)	5.9	(4.9)	8.8
Realized Net Performance Fees	7.7	6.4	13.4	13.2
Realized Investment Income (Loss)	1.1	3.1	2.7	5.9
Distributable Earnings	3.7	15.4	11.2	27.9
Segment assets	783.8		783.8
Operating Segments | Real Assets
Fund level fee revenues
Fund management fees	60.3	69.3	192.0	197.1
Portfolio advisory fees, net	0.0	0.1	0.1	0.4
Transaction fees, net	0.0	0.1	0.0	0.4
Total fund level fee revenues	60.3	69.5	192.1	197.9
Performance fees
Realized	19.2	57.7	79.8	112.5
Unrealized	2.0	(9.3)	165.8	(38.3)
Total performance fees	21.2	48.4	245.6	74.2
Investment income (loss)
Realized	(14.1)	(4.9)	(21.4)	(94.7)
Unrealized	4.5	2.1	6.5	58.4
Total investment income (loss)	(9.6)	(2.8)	(14.9)	(36.3)
Interest income	0.4	0.1	1.3	0.2
Other income	0.4	0.8	1.0	2.4
Total revenues	72.7	116.0	425.1	238.4
Compensation and benefits
Direct base compensation	17.2	20.4	55.4	56.4
Indirect base compensation	8.9	9.7	28.2	30.8
Equity-based compensation	7.1	6.2	20.3	19.6
Performance fee related
Realized	8.7	25.5	34.8	46.0
Unrealized	(15.7)	7.2	55.2	28.4
Total compensation and benefits	26.2	69.0	193.9	181.2
General, administrative, and other indirect expenses	37.2	17.0	70.7	52.4
Depreciation and amortization expense	1.4	1.2	4.4	3.1
Interest expense	4.1	2.6	12.1	7.9
Total expenses	68.9	89.8	281.1	244.6
Economic Net Income (Loss)	3.8	26.2	144.0	(6.2)
Net Performance Fees	28.2	15.7	155.6	(0.2)
Investment Income (Loss)	(9.6)	(2.8)	(14.9)	(36.3)
Equity-based compensation	7.1	6.2	20.3	19.6
Reserve for Litigation and Contingencies	21.6		21.6
Fee Related Earnings	13.9	19.5	45.2	49.9
Realized Net Performance Fees	10.5	32.2	45.0	66.5
Realized Investment Income (Loss)	(14.1)	(4.9)	(21.4)	(94.7)
Distributable Earnings	10.3	46.8	68.8	21.7
Segment assets	1,549.6		1,549.6
Operating Segments | Investment Solutions
Fund level fee revenues
Fund management fees	33.1	37.8	103.7	116.1
Portfolio advisory fees, net	0.8	0.0	0.8	0.0
Transaction fees, net	0.0	0.0	0.0	0.0
Total fund level fee revenues	33.9	37.8	104.5	116.1
Performance fees
Realized	36.3	5.0	42.7	13.2
Unrealized	(6.8)	31.4	19.9	122.1
Total performance fees	29.5	36.4	62.6	135.3
Investment income (loss)
Realized	0.0	0.0	0.0	0.1
Unrealized	0.2	0.1	(0.8)	0.3
Total investment income (loss)	0.2	0.1	(0.8)	0.4
Interest income	0.1	0.0	0.3	0.1
Other income	0.2	0.3	0.4	1.0
Total revenues	63.9	74.6	167.0	252.9
Compensation and benefits
Direct base compensation	16.3	19.8	49.9	60.6
Indirect base compensation	2.7	2.9	8.6	9.8
Equity-based compensation	1.6	2.6	5.1	7.3
Performance fee related
Realized	35.8	4.4	41.2	10.9
Unrealized	(9.7)	28.0	13.3	113.6
Total compensation and benefits	46.7	57.7	118.1	202.2
General, administrative, and other indirect expenses	17.3	10.7	34.6	31.4
Depreciation and amortization expense	0.9	0.8	2.6	3.0
Interest expense	1.5	1.4	4.5	4.4
Total expenses	66.4	70.6	159.8	241.0
Economic Net Income (Loss)	(2.5)	4.0	7.2	11.9
Net Performance Fees	3.4	4.0	8.1	10.8
Investment Income (Loss)	0.2	0.1	(0.8)	0.4
Equity-based compensation	1.6	2.6	5.1	7.3
Reserve for Litigation and Contingencies	9.6		9.6
Fee Related Earnings	5.1	2.5	14.6	8.0
Realized Net Performance Fees	0.5	0.6	1.5	2.3
Realized Investment Income (Loss)	0.0	0.0	0.0	0.1
Distributable Earnings	5.6	$ 3.1	16.1	$ 10.4
Segment assets	$ 919.5		$ 919.5