Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	$ 8,177	$ 7,757
Segment earnings (loss)	501	(36)
Realized investment gains, net of taxes	27	93
Shareholders' Net Income	528	57
Operating Segments [Member] | Global Health Benefits Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	6,546	6,297
Segment earnings (loss)	439	427
Operating Segments [Member] | Global Supplemental Benefits Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	690	612
Segment earnings (loss)	53	55
Operating Segments [Member] | Group Disability And Life Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	915	858
Segment earnings (loss)	67	(2)
Operating Segments [Member] | Other Operations Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	30	(7)
Segment earnings (loss)	17	(462)
Corporate [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and Other revenues	(4)	(3)
Segment earnings (loss)	$ (75)	$ (54)