Consolidated Statements of Comprehensive Income Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net Income (Loss) Attributable to Parent	$ 1,933	$ 1,774	$ 1,344
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	(163)	375	(597)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(10)	(182)	(253)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(165)	(26)	252
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(338)	167	(598)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 1,595	$ 1,941	$ 746