Consolidated Statements of Comprehensive Income Consolidated Statement of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	$ 53	$ 63
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	27	(29)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	$ (43)	$ 18