Consolidated Statement of Income (USD $) In Millions, except Per Share data, 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
Revenues
Premiums									$ 23,713		$ 22,637		$ 22,357
Net investment income									2,787		2,716		2,889
Fee income									438		395		323
Net realized investment gains									79	[1]	166	[1]	51	[1]
Other revenues									145		277		120
Total revenues	6,783	6,886	6,785	6,708	6,737	6,452	6,674	6,328	27,162		26,191		25,740
Claims and expenses
Claims and claim adjustment expenses									13,870		13,307		14,676
Amortization of deferred acquisition costs									3,882		3,821		3,910
General and administrative expenses									3,952		3,757		3,610
Interest expense									369		361		378
Total claims and expenses	5,323	5,628	5,884	5,238	5,366	5,275	5,497	5,108	22,073		21,246		22,574
Income before income taxes	1,460	1,258	901	1,470	1,371	1,177	1,177	1,220	5,089		4,945		3,166
Income tax expense	422	339	218	418	383	313	252	324	1,397		1,272		693
Net income	$ 1,038	$ 919	$ 683	$ 1,052	$ 988	$ 864	$ 925	$ 896	$ 3,692		$ 3,673		$ 2,473
Net income per share
Basic	$ 3.15	$ 2.72	$ 1.98	$ 2.98	$ 2.73	$ 2.33	$ 2.44	$ 2.36	$ 10.82		$ 9.84		$ 6.35
Diluted	$ 3.11	$ 2.69	$ 1.95	$ 2.95	$ 2.70	$ 2.30	$ 2.41	$ 2.33	$ 10.70		$ 9.74		$ 6.30
Weighted average number of common shares outstanding
Basic									338.8		370.3		386.2
Diluted									342.5		374.3		389.8

[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.