Other Comprehensive Income and Accumulated Other Comprehensive Income (details) - Reclassifications (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement									$ (79)	[1]	$ (166)	[1]	$ (51)	[1]
Reclassification adjustment impacting general and administrative expense on the income statement									3,952		3,757		3,610
Total reclassifications	(1,460)	(1,258)	(901)	(1,470)	(1,371)	(1,177)	(1,177)	(1,220)	(5,089)		(4,945)		(3,166)
Income tax benefit	(422)	(339)	(218)	(418)	(383)	(313)	(252)	(324)	(1,397)		(1,272)		(693)
Amounts reclassified from accumulated other comprehensive income, net of taxes	(1,038)	(919)	(683)	(1,052)	(988)	(864)	(925)	(896)	(3,692)		(3,673)		(2,473)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Total reclassifications									28		52		21
Income tax benefit									10		15		7
Amounts reclassified from accumulated other comprehensive income, net of taxes									18		37		14
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement									(36)		(66)		(75)
Income tax benefit									(12)		(23)		(26)
Amounts reclassified from accumulated other comprehensive income, net of taxes									(24)		(43)		(49)
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement									4		5		8
Income tax benefit									1		1		3
Amounts reclassified from accumulated other comprehensive income, net of taxes									3		4		5
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting general and administrative expense on the income statement									60		105		88
Income tax benefit									21		37		30
Amounts reclassified from accumulated other comprehensive income, net of taxes									39		68		58
Net Unrealized Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassification adjustment impacting realized gains on the income statement											8
Amounts reclassified from accumulated other comprehensive income, net of taxes											$ 8

[1] Total other-than-temporary impairment (OTTI) gains (losses) were $(22) million, $(10) million and $27 million for the years ended December 31, 2014, 2013 and 2012, respectively. Of total OTTI, credit losses of $(26) million, $(15) million and $(15) million for the years ended December 31, 2014, 2013 and 2012 respectively, were recognized in net realized investment gains. In addition, unrealized gains from other changes in total OTTI of $4 million, $5 million and $42 million for the years ended December 31, 2014, 2013 and 2012, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income.