Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities
Net income	$ 2,399.5	$ 1,154.3	$ 1,459.4
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	107.8	83.1	24.5
Amortization of deferred financing fees	1.3	1.1	1.6
Equity-based compensation	201.7
Non-cash equity issued for affiliate debt financing			214.0
Non-cash performance fees	(192.6)	62.6	(1,344.4)
Loss on early extinguishment of debt			2.5
Other non-cash amounts	7.1	31.5	(25.9)
Consolidated Funds related:
Realized/unrealized (gain) loss on investments of Consolidated Funds	(2,571.2)	284.4	(502.0)
Realized/unrealized loss from loans payable of Consolidated Funds	926.2	56.7	752.4
Purchases of investments by Consolidated Funds	(7,176.3)	(6,818.9)	(3,254.3)
Proceeds from sale and settlements of investments by Consolidated Funds	8,530.5	7,970.8	5,432.6
Non-cash interest income, net	(80.6)	(96.0)	(113.7)
Change in cash and cash equivalents held at Consolidated Funds	1,274.7	243.7	149.8
Change in other receivables held at Consolidated Funds	41.5	8.5	(58.5)
Change in other liabilities held at Consolidated Funds	(1,038.9)	(142.8)	126.7
Investment income	(32.1)	(82.8)	(69.0)
Purchases of investments (includes investment in NGP Management in 2012 of $385.8)	(520.3)	(128.4)	(95.5)
Proceeds from the sale of investments	199.9	300.9	41.9
Purchases of trading securities	(20.1)	(6.7)	(19.3)
Proceeds from sale of trading securities and other	15.7	0.2	7.9
Changes in deferred taxes	(9.3)	(19.8)	2.0
Change in due from affiliates and other receivables	10.1	16.3	14.5
Change in deposits and other	9.4	(16.5)	(20.7)
Change in accounts payable, accrued expenses and other liabilities	3.4	(51.6)	41.9
Change in accrued compensation and benefits	(5.3)	(91.7)	121.8
Change in due to affiliates	(23.6)	29.8	(5.9)
Change in deferred revenue	(30.1)	(110.7)	(7.3)
Net cash provided by operating activities	2,028.4	2,678.0	2,877.0
Cash flows from investing activities
Change in restricted cash	(9.6)	(8.6)	(0.3)
Purchases of fixed assets, net	(32.7)	(34.2)	(21.2)
Purchases of intangible assets	(41.0)	(8.1)	(58.5)
Acquisitions, net of cash acquired	(42.8)	(53.9)	(105.6)
Net cash used in investing activities	(126.1)	(104.8)	(185.6)
Cash flows from financing activities
Borrowings under credit facility	820.0	520.5
Repayments under credit facility	(744.6)	(209.7)
Proceeds from loans payable			994.0
Payments on loans payable	(310.0)	(307.5)	(411.9)
Net payment on loans payable of Consolidated Funds	(1,415.2)	(1,204.7)	(2,280.5)
Payments of contingent consideration	(10.0)
Net proceeds from issuance of common units in initial public offering	615.8
Distributions to common unitholders	(11.7)
Contributions from predecessor owners	9.3	15.1	46.1
Distributions to predecessor owners	(452.3)	(1,498.4)	(787.8)
Contributions from non-controlling interest holders	2,044.7	1,251.1	48.4
Distributions to non-controlling interest holders	(2,406.8)	(1,312.0)	(157.4)
Change in due to/from affiliates financing activities	0.7	39.0	16.4
Change in due to/from affiliates and other receivables of Consolidated Funds	18.8	27.6	(0.7)
Net cash used in financing activities	(1,841.3)	(2,679.0)	(2,533.4)
Effect of foreign exchange rate changes	(3.5)	(1.5)	(29.2)
Increase (decrease) in cash and cash equivalents	57.5	(107.3)	128.8
Cash and cash equivalents, beginning of period	509.6	616.9	488.1
Cash and cash equivalents, end of period	567.1	509.6	616.9
Supplemental cash disclosures
Cash paid for interest	24.7	59.2	15.8
Cash paid for income taxes	56.1	30.0	24.0
Supplemental non-cash disclosures
Non-cash contributions from predecessor owners			5.6
Non-cash distributions to predecessor owners	402.5	(51.5)	522.3
Non-cash contributions from non-controlling interest holders	127.7	95.2	4.7
Non-cash distributions to non-controlling interest holders	77.8	119.2
Reorganization:
Transfer of members' equity to non-controlling interests in consolidated entities	120.3
Deferred taxes from transfer of ownership interests	9.4
Exchange of CalPERS equity interests:
Deferred tax asset	41.7
Tax receivable agreement liability	34.9
Total partners' capital	6.8
Noncontrolling interest in AlpInvest [Member]
Supplemental non-cash disclosures
Non-cash acquisition		8,434.7
Emerging Sovereign Group LLC [Member]
Supplemental non-cash disclosures
Non-cash acquisition		510.1
Collateralized Loan Obligations [Member]
Supplemental non-cash disclosures
Net assets related to consolidation	357.3	46.7	1,213.3
Claren Road [Member]
Supplemental non-cash disclosures
Net assets related to consolidation			$ 694.0