Fair Value Measurements (Details 2) (Level 3 [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Interest rate [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	$ 75	$ 99
Gain (losses) included in earnings	53	9
Purchases, sales, issuances and settlements		(18)
Net transfers into (out of) Level 3		(15)
Purchases	12
Sales	(44)
Issuances
Transfers into Level 3	13
Transfers out of Level 3	(71)
Ending Balance	38	75
Unrealized gains (losses) included in earnings
Energy and commodity [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	1	0
Gain (losses) included in earnings	(1)	(1)
Purchases, sales, issuances and settlements		(1)
Net transfers into (out of) Level 3		3
Issuances
Ending Balance	(1)	1
Unrealized gains (losses) included in earnings
Credit [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	11	9
Gain (losses) included in earnings	(40)	(6)
Purchases, sales, issuances and settlements		8
Sales	(1)
Issuances
Settlements	9
Ending Balance	(21)	11
Unrealized gains (losses) included in earnings
Principal Direct Investments [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	372	538
Gain (losses) included in earnings	(2)	(1)
Purchases, sales, issuances and settlements		(157)
Net transfers into (out of) Level 3		(8)
Purchases	39
Sales	(52)
Issuances
Transfers out of Level 3	(132)
Ending Balance	225	372
Unrealized gains (losses) included in earnings	11	(22)
Principal Indirect Investments [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	526	497
Gain (losses) included in earnings	70	67
Purchases, sales, issuances and settlements		(38)
Purchases	66
Sales	(80)
Issuances
Transfers out of Level 3	(109)
Ending Balance	473	526
Unrealized gains (losses) included in earnings	45	47
Equity and Mezzanine Direct Investments [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	20	26
Gain (losses) included in earnings	20	9
Purchases, sales, issuances and settlements		(21)
Net transfers into (out of) Level 3		6
Issuances
Settlements	(25)
Ending Balance	15	20
Unrealized gains (losses) included in earnings	38	90
Equity and Mezzanine Indirect Investments [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	30	31
Gain (losses) included in earnings		(7)
Purchases, sales, issuances and settlements		6
Purchases	14
Issuances
Settlements	(5)
Transfers out of Level 3	(3)
Ending Balance	36	30
Unrealized gains (losses) included in earnings	(3)	(7)
Mortgage Backed Securities, Other [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	1	29
Gain (losses) included in earnings		2
Purchases, sales, issuances and settlements		(30)
Issuances
Transfers into Level 3	34
Ending Balance	35	1
Unrealized gains (losses) included in earnings		(4)
Commercial Loan [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	0	19
Gain (losses) included in earnings		(2)
Purchases, sales, issuances and settlements		(7)
Net transfers into (out of) Level 3		(10)
Issuances
Ending Balance	0	0
Unrealized gains (losses) included in earnings		2
Other Debt Securities [Member]
Changes in Level 3 Fair Value Measurements
Beginning Balance	21	423
Gain (losses) included in earnings	2	(3)
Purchases, sales, issuances and settlements		(399)
Issuances
Settlements	(23)
Ending Balance	0	21
Unrealized gains (losses) included in earnings	$ 2	$ (3)