Segment Information (Details 3) (USD $) In Millions, 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
Realized Investment Gains Losses From Continuing Operations [Abstract]
Total realized investment gains (losses)																	$ 44	$ 62	$ 75
Less income taxes (benefits)																	13	21	25
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest																	31	41	50
Segment Reporting Information [Line Items]
Premiums and fees and other revenues																	26,308	19,210	18,528
Mail order pharmacy revenues																	1,623	1,447	1,420
Net investment income																	1,144	1,146	1,105
Realized investment gains (losses)																	44	62	75
Total revenues	7,620		7,323		7,422		6,754		5,425		5,574		5,479		5,387		29,119	21,865	21,128
Depreciation and amortization																	560	345	292
Income taxes																	853	615	519
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest																	31	41	50
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
Operating Segments [Member]
Segment Reporting Information [Line Items]
Shareholders' net income																	1,592	1,219	1,229
Unallocated Amount to Segment [Member]
Realized Investment Gains Losses From Continuing Operations [Abstract]
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest																	31	41	50
Segment Reporting Information [Line Items]
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest																	$ 31	$ 41	$ 50

[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.