Investments and Related Matters Investment Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Investments [Line Items]
Investments	$ 9,987		$ 9,987		$ 15,351
Securities sold, not yet purchased, at fair value	1,210		1,210		794
Investment Segment [Member]
Schedule of Investments [Line Items]
Investments	9,317		9,317		14,553
Securities sold, not yet purchased, at fair value	1,210		1,210		794
Portion of trading gains (loss) that relates to trading securities still held	754	$ (2,200)	626	$ (1,900)
Investment Segment [Member] | Equity securities:
Schedule of Investments [Line Items]
Investments	9,028		9,028		14,324
Securities sold, not yet purchased, at fair value	1,154		1,154		794
Investment Segment [Member] | Corporate debt:
Schedule of Investments [Line Items]
Investments	289		289		72
Investment Segment [Member] | Basic materials | Equity securities:
Schedule of Investments [Line Items]
Investments	904		904		563
Investment Segment [Member] | Communications | Equity securities:
Schedule of Investments [Line Items]
Investments	176		176		407
Investment Segment [Member] | Consumer, non-cyclical | Equity securities:
Schedule of Investments [Line Items]
Investments	2,729		2,729		3,684
Securities sold, not yet purchased, at fair value	4		4		794
Investment Segment [Member] | Consumer, non-cyclical | Corporate debt:
Schedule of Investments [Line Items]
Investments	103		103		0
Investment Segment [Member] | Consumer, cyclical | Equity securities:
Schedule of Investments [Line Items]
Investments	298		298		115
Securities sold, not yet purchased, at fair value	891		891		0
Investment Segment [Member] | Consumer, cyclical | Corporate debt:
Schedule of Investments [Line Items]
Investments	170		170		55
Investment Segment [Member] | Diversified | Equity securities:
Schedule of Investments [Line Items]
Investments	19		19		17
Investment Segment [Member] | Energy | Equity securities:
Schedule of Investments [Line Items]
Investments	1,464		1,464		1,461
Securities sold, not yet purchased, at fair value	14		14		0
Investment Segment [Member] | Energy | Corporate debt:
Schedule of Investments [Line Items]
Securities sold, not yet purchased, at fair value	56		56		0
Investment Segment [Member] | Financial | Equity securities:
Schedule of Investments [Line Items]
Investments	2,167		2,167		2,094
Securities sold, not yet purchased, at fair value	129		129		0
Investment Segment [Member] | Financial | Corporate debt:
Schedule of Investments [Line Items]
Investments	4		4		4
Investment Segment [Member] | Financial | Mortgage-backed securities:
Schedule of Investments [Line Items]
Investments	0		0		157
Investment Segment [Member] | Industrial | Equity securities:
Schedule of Investments [Line Items]
Investments	240		240		188
Securities sold, not yet purchased, at fair value	116		116		0
Investment Segment [Member] | Technology | Equity securities:
Schedule of Investments [Line Items]
Investments	1,031		1,031		5,795
Investment Segment [Member] | Sovereign debt | Corporate debt:
Schedule of Investments [Line Items]
Investments	0		0		13
Investment Segment [Member] | Utilities | Corporate debt:
Schedule of Investments [Line Items]
Investments	$ 12		$ 12		$ 0
Herbalife [Member] | Investment Segment [Member]
Schedule of Investments [Line Items]
Ownership percentage in investment measured at fair value that would otherwise be accounted for under equity method	21.10%		21.10%
Unrealized gain on investment at fair value that would otherwise be accounted for under equity method	$ 52		$ 119
Fair value of equity method investment under fair value option	$ 973		$ 973