Quarterly Financial Data (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended															12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Quarterly Results [Abstract]
Total revenues	$ 8,151		$ 8,066	$ 7,980		$ 8,183		$ 7,620		$ 7,323		$ 7,422		$ 6,754		$ 32,380	$ 29,119	$ 21,865
Income from Continuing Operations before Income Tax (Foreign)	536		799	767		74		619		718		588		552
Shareholders' net income	361	[1]	553	505	[2]	57	[3]	406	[4]	466	[5]	380	[6]	371	[7]	1,476	1,623	1,260
Shareholders Net Income Per Share [Abstract]
EPS, basic	$ 1.32		$ 1.99	$ 1.79		$ 0.20		$ 1.43		$ 1.64		$ 1.33		$ 1.30		$ 5.28	$ 5.70	$ 4.65
EPS, diluted	$ 1.29		$ 1.95	$ 1.76		$ 0.20		$ 1.41		$ 1.61		$ 1.31		$ 1.28		$ 5.18	$ 5.61	$ 4.59
Stock And Dividend Data [Abstract]
Price Range Common Stock High	$ 88.57		$ 84.68	$ 73.13		$ 63.19		$ 54.53		$ 47.92		$ 49.63		$ 49.89
Price Range Common Stock Low	$ 72.64		$ 71.12	$ 61.88		$ 53.91		$ 47.31		$ 39.34		$ 42.21		$ 41.27
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]
GMIB (gain) loss						(25)		(7)		(32)		51		(41)
Charge for reinsurance transaction						507
Charge related to regulatory matters						51
Charge related to partnership agreement				24
Charges associated with an organizational efficiency plan	40									50
Acquisition costs										12				28
Litigation charges								$ 68						$ 13

[1] The fourth quarter of 2013 includes an after-tax charge of $40 million for an organizational efficiency plan.

[2] The second quarter of 2013 includes an after-tax charge of $24 million for the Pharmacy Benefits Manager (“PBM”) partnering agreement with Catamaran.

[3] The first quarter of 2013 includes an after-tax gain of $25 for the GMIB business, an after-tax charge of $507 million for the transaction with Berkshire to effectively exit the Run-off Reinsurance business, and an after-tax charge of $51 million related to the disability claims regulatory matter in the Group Disability and Life segment.

[4] 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.

[5] 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 an organizational efficiency plan.

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

[7] 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.