Quarterly Financial Data (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Quarterly Results [Abstract]
Total revenues	$ 7,620		$ 7,323		$ 7,422		$ 6,754		$ 5,425		$ 5,574		$ 5,479		$ 5,387		$ 29,119	$ 21,865	$ 21,128
Income from Continuing Operations before Income Tax (Foreign)	619		718		588		552		432		273		592		579
Shareholders' net income	406	[1]	466	[2]	380	[3]	371	[4]	273	[5]	183	[6]	391	[7]	413	[8]	1,623	1,260	1,279
Shareholders Net Income Per Share [Abstract]
Shareholders' net income per share basic	$ 1.43		$ 1.64		$ 1.33		$ 1.30		$ 0.99		$ 0.68		$ 1.46		$ 1.53		$ 5.70	$ 4.65	$ 4.69
Shareholders' net income per share diluted	$ 1.41		$ 1.61		$ 1.31		$ 1.28		$ 0.98		$ 0.67		$ 1.43		$ 1.51		$ 5.61	$ 4.59	$ 4.65
Stock And Dividend Data [Abstract]
Price Range Common Stock High	$ 54.53		$ 47.92		$ 49.63		$ 49.89		$ 47.61		$ 52.95		$ 51.81		$ 44.29
Price Range Common Stock Low	$ 47.31		$ 39.34		$ 42.21		$ 41.27		$ 38.82		$ 40.24		$ 42.80		$ 36.76
Dividends Declared Per Share	$ 0		$ 0		$ 0		$ 0.04		$ 0		$ 0		$ 0		$ 0.04		$ 0.04	$ 0.04	$ 0.04
Quarterly Financial Data Text Details [Abstract]
Quarterly Financial Information Quarterly Charges And Credits Amount Affecting Comparability Resolution Federal Tax Matter															24
Quarterly Financial Information Quarterly Charges And Credits Amount Affecting Comparability Cost Reduction Program			(50)
Quarterly Financial Information Quarterly Charges And Credits Amount Affecting Comparability Acquisition Costs			(12)				(28)		(31)
Quarterly Financial Information Quarterly Guaranteed Income Benefits Expense After Tax	7		32		(51)		41		7		(134)		(21)		13
Quarterly Financial Information Quarterly Charges And Credits Amount Affecting Comparability Litigation Charges	$ (68)						$ (13)

[1] The fourth quarter of 2012 includes an after-tax gain of $7 million for the GMIB business and an after-tax charge of $68 million for litigation matters

[2] The third quarter of 2012 includes an after-tax gain of $32 million for the GMIB business, an after-tax charge of $12 million for costs associated with acquisitions, and an after-tax charge of $50 million for costs associated with a realignment and efficiency plan.

[3] The second quarter of 2012 includes an after-tax loss of $51 million for the GMIB business.

[4] The first quarter of 2012 includes an after-tax gain of $41 million for the GMIB business, an after-tax charge of $28 million for costs associated with acquisitions, and an after-tax charge of $13 million for costs associated a litigation matter in Global Health Care.

[5] The fourth quarter of 2011 includes an after-tax gain of $7 million for the GMIB business and, an after-tax charge of $31 million for costs associated with acquisitions.

[6] The third quarter of 2011 includes an after-tax loss of $134 million for the GMIB business.

[7] The second quarter of 2011 includes an after-tax loss of $21 million for the GMIB business.

[8] The first quarter of 2011 includes an after-tax gain of $13 million for the GMIB business and a net tax benefit of $24 million related to the resolution of a Federal tax matter.