Fair Value Measurements Investment Fair Value (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Investments [Abstract]
Investments	$ 4,912		$ 8,938
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	314		4,476
Investment Segment [Member]
Investments [Abstract]
Investments	4,500		8,448
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	314		4,476
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Investments [Abstract]
Investments	3,531		7,119
Derivative contracts, Assets at fair value	0	[1]	0	[1]
Assets, Fair Value Disclosure	3,531		7,119
Securities sold, not yet purchased, at fair value: [Abstract]
Derivative Liabilities	0	[2]	0	[2]
Liabilities, Fair Value	295		4,466
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Investments [Abstract]
Trading securities	3,531		7,119
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	295		4,466
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Basic materials [Member]
Investments [Abstract]
Trading securities	84		128
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Communications [Member]
Investments [Abstract]
Trading securities	211		2,593
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, non-cyclical [Member]
Investments [Abstract]
Trading securities	1,300		1,778
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	409		376
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	295		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Energy Segment [Member]
Investments [Abstract]
Trading securities	966		1,644
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	237		263
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Funds [Member]
Investments [Abstract]
Trading securities	0		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		4,466
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Industrial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Technology [Member]
Investments [Abstract]
Trading securities	268		254
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	56		83
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Communications [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Sovereign debt [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investments [Abstract]
Investments	676		1,040
Derivative contracts, Assets at fair value	0	[1]	3	[1]
Assets, Fair Value Disclosure	676		1,043
Securities sold, not yet purchased, at fair value: [Abstract]
Derivative Liabilities	383	[2]	42	[2]
Liabilities, Fair Value	402		52
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Investments [Abstract]
Trading securities	417		486
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	19		10
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Basic materials [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Communications [Member]
Investments [Abstract]
Trading securities	43		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, non-cyclical [Member]
Investments [Abstract]
Trading securities	0		26
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	3		378
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Energy Segment [Member]
Investments [Abstract]
Trading securities	0		29
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Funds [Member]
Investments [Abstract]
Trading securities	304		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	19		10
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Industrial [Member]
Investments [Abstract]
Trading securities	0		32
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Technology [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	67		21
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Investments [Abstract]
Trading securities	82		387
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Communications [Member]
Investments [Abstract]
Trading securities	0		84
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	0		150
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Financial [Member]
Investments [Abstract]
Trading securities	48		109
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Sovereign debt [Member]
Investments [Abstract]
Trading securities	3		10
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	31		34
Investment Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	177		167
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investments [Abstract]
Investments	293		289
Derivative contracts, Assets at fair value	0	[1]	0	[1]
Assets, Fair Value Disclosure	293		289
Securities sold, not yet purchased, at fair value: [Abstract]
Derivative Liabilities	0	[2]	0	[2]
Liabilities, Fair Value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Investments [Abstract]
Trading securities	0		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Basic materials [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Communications [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, non-cyclical [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	0		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Energy Segment [Member]
Investments [Abstract]
Trading securities	0		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Funds [Member]
Investments [Abstract]
Trading securities	0		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Industrial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Technology [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Investments [Abstract]
Trading securities	293		289
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Communications [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	293		289
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Sovereign debt [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	0		0
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]
Investments [Abstract]
Investments	4,500		8,448
Derivative contracts, Assets at fair value	0	[1]	3	[1]
Assets, Fair Value Disclosure	4,500		8,451
Securities sold, not yet purchased, at fair value: [Abstract]
Derivative Liabilities	383	[2]	42	[2]
Liabilities, Fair Value	697		4,518
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Investments [Abstract]
Trading securities	3,948		7,605
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	314		4,476
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Basic materials [Member]
Investments [Abstract]
Trading securities	84		128
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Communications [Member]
Investments [Abstract]
Trading securities	254		2,593
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, non-cyclical [Member]
Investments [Abstract]
Trading securities	1,300		1,804
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	412		754
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	295		0
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Energy Segment [Member]
Investments [Abstract]
Trading securities	966		1,673
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	0		0
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	237		263
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Funds [Member]
Investments [Abstract]
Trading securities	304		0
Securities sold, not yet purchased, at fair value: [Abstract]
Securities sold, not yet purchased, at fair value	19		4,476
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Industrial [Member]
Investments [Abstract]
Trading securities	0		32
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Technology [Member]
Investments [Abstract]
Trading securities	268		254
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	123		104
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Investments [Abstract]
Trading securities	375		676
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Communications [Member]
Investments [Abstract]
Trading securities	0		84
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Consumer, cyclical [Member]
Investments [Abstract]
Trading securities	293		439
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Financial [Member]
Investments [Abstract]
Trading securities	48		109
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Sovereign debt [Member]
Investments [Abstract]
Trading securities	3		10
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt [Member] | Utilities [Member]
Investments [Abstract]
Trading securities	31		34
Investment Segment [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities [Member] | Financial [Member]
Investments [Abstract]
Trading securities	$ 177		$ 167

[1] Included in other assets in our consolidated balance sheets.

[2] Included in accrued expenses and other liabilities in our consolidated balance sheets.