Fair Value Measurements (Details 6) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011 Private equity funds Y	Dec. 31, 2010 Private equity funds
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	$ 7,453	$ 7,920
Unfunded Commitments	1,389	1,496
Investments of entities classified as held for sale		415
Private equity funds:
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	4,574	4,265
Unfunded Commitments	1,385	1,474
Expected remaining lives that funds in some cases extend beyond (in years)	10
Investment redemption notice period (in days/years)	1 years
Private equity funds: | Expected remaining lives of less than 3 years
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
First threshold level of remaining lives (in years)	3
Percentage of hedge fund investments that cannot be redeemed, either in whole or in part	34.00%
Private equity funds: | Expected remaining lives of less than 3 to 7 years
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Second threshold level of remaining lives (in years)	7
Percentage of hedge fund investments that cannot be redeemed, either in whole or in part	52.00%
Private equity funds: | Expected remaining lives of less than 7 to 10 years
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Third threshold level of remaining lives (in years)	10
Percentage of hedge fund investments that cannot be redeemed, either in whole or in part	14.00%
Leveraged buyout
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	3,399	3,137
Unfunded Commitments	1,046	1,151
Non-U.S.
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	190	172
Unfunded Commitments	60	67
Venture capital
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	490	325
Unfunded Commitments	105	42
Distressed
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	223	258
Unfunded Commitments	64	67
Other.
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	272	373
Unfunded Commitments	110	147
Hedge funds:
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	2,879	3,655
Unfunded Commitments	4	22
Hedge fund investments redeemable monthly (as a percent)	12.00%
Hedge fund investments redeemable quarterly (as a percent)	53.00%
Hedge fund investments redeemable semi-annually (as a percent)	8.00%
Hedge fund investments redeemable annually (as a percent)	27.00%
Hedge fund investments redemption notices of less than 90 days (as a percent)	78.00%
Percentage of hedge fund investments that cannot be redeemed, either in whole or in part	52.00%
Investment redemption notice period (in days/years)	1 day to 180 days
Event-driven
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	839	1,310
Unfunded Commitments	2	2
Long-short
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	905	1,038
Relative value
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	115	230
Distressed.
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	317	369
Unfunded Commitments	2	20
Other hedge funds
Investments in Certain Entities Carried at Fair Value Using Net Asset Value per Share
Fair Value Using Net Asset Value	$ 703	$ 708