Investments and Related Matters Investment Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Schedule of Investments [Line Items]
Investments	$ 10,026		$ 15,351
Securities sold, not yet purchased, at fair value	1,052		794
Investment Segment [Member]
Schedule of Investments [Line Items]
Investments	9,271		14,553
Securities sold, not yet purchased, at fair value	1,052		794
Portion of trading gains (loss) that relates to trading securities still held	(174)	$ 458
Investment Segment [Member] | Equity securities:
Schedule of Investments [Line Items]
Investments	9,001		14,324
Securities sold, not yet purchased, at fair value	998		794
Investment Segment [Member] | Corporate debt:
Schedule of Investments [Line Items]
Investments	132		72
Investment Segment [Member] | Basic materials | Equity securities:
Schedule of Investments [Line Items]
Investments	860		563
Investment Segment [Member] | Communications | Equity securities:
Schedule of Investments [Line Items]
Investments	218		407
Investment Segment [Member] | Consumer, non-cyclical | Equity securities:
Schedule of Investments [Line Items]
Investments	3,035		3,684
Securities sold, not yet purchased, at fair value	0		794
Investment Segment [Member] | Consumer, cyclical | Equity securities:
Schedule of Investments [Line Items]
Investments	163		115
Securities sold, not yet purchased, at fair value	847		0
Investment Segment [Member] | Consumer, cyclical | Corporate debt:
Schedule of Investments [Line Items]
Investments	116		55
Investment Segment [Member] | Diversified | Equity securities:
Schedule of Investments [Line Items]
Investments	16		17
Investment Segment [Member] | Energy | Equity securities:
Schedule of Investments [Line Items]
Investments	1,292		1,461
Investment Segment [Member] | Energy | Corporate debt:
Schedule of Investments [Line Items]
Securities sold, not yet purchased, at fair value	54		0
Investment Segment [Member] | Financial | Equity securities:
Schedule of Investments [Line Items]
Investments	1,921		2,094
Securities sold, not yet purchased, at fair value	151		0
Investment Segment [Member] | Financial | Corporate debt:
Schedule of Investments [Line Items]
Investments	4		4
Investment Segment [Member] | Financial | Mortgage-backed securities:
Schedule of Investments [Line Items]
Investments	138		157
Investment Segment [Member] | Industrial | Equity securities:
Schedule of Investments [Line Items]
Investments	222		188
Investment Segment [Member] | Technology | Equity securities:
Schedule of Investments [Line Items]
Investments	1,274		5,795
Investment Segment [Member] | Sovereign debt | Corporate debt:
Schedule of Investments [Line Items]
Investments	0		13
Investment Segment [Member] | Utilities | Corporate debt:
Schedule of Investments [Line Items]
Investments	$ 12		$ 0