Investments and Related Matters Other Segments (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Investments	$ 14,466	$ 14,466	$ 14,500
Other Segments [Member]
Schedule of Investments [Line Items]
Equity method investments	306	306	298
Other investments	208	208	241
Investments	514	514	539
Energy Segment [Member]
Schedule of Investments [Line Items]
Investments	0	0	$ 77
Proceeds from Sale of Available-for-sale Securities	38	68
Cost basis of available for sale securities sold during the period		48
Reclassification adjustment from AOCI for sale of securities, before tax		20
Cost basis of available for sale securities transferred to trading securities		26
Available-for-sale Securities, Transfers to Trading, Gains (Losses)		$ 12
Trading Securities, Realized Gain	$ 1