Recent Accounting Pronouncements (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			3 Months Ended				3 Months Ended		12 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Mar. 31, 2012 International Segment [Member]	Mar. 31, 2011 International Segment [Member]	Mar. 31, 2011 Accounting Standards Update 2010-26 [Member] Scenario, Previously Reported [Member]	Dec. 31, 2011 Accounting Standards Update 2010-26 [Member] Scenario, Previously Reported [Member]	Mar. 31, 2011 Accounting Standards Update 2010-26 [Member] Scenario, Previously Reported [Member] International Segment [Member]	Mar. 31, 2011 Accounting Standards Update 2010-26 [Member] Restatement Adjustment [Member]	Dec. 31, 2011 Accounting Standards Update 2010-26 [Member] Restatement Adjustment [Member]	Mar. 31, 2011 Accounting Standards Update 2010-26 [Member] Restatement Adjustment [Member] International Segment [Member]
Consolidated Statement of Income
Revenue, excluding other revenues		$ 5,377				$ 5,377			$ 0
Other revenues	(40)	34				36			(2)
Total revenues	6,788	5,411				5,413			(2)
Benefits and expenses, excluding other operating expenses		3,331				3,331			0
Other operating expenses	1,841	1,501				1,482			19
Total benefits and expenses	6,236	4,832				4,813			19
Income before Income Taxes	552	579				600			(21)
Current income taxes	135	22				22			0
Deferred income taxes	46	143				148			(5)
Total taxes	181	165				170			(5)
Net Income	371	414				430			(16)
Less: Net Income Attributable to Noncontrolling Interest	0	1				1			0
Shareholders' net income	371	413				429			(16)	(67)
Earnings per share:
Basic	$ 1.30	$ 1.53				$ 1.59			$ (0.06)
Diluted	$ 1.28	$ 1.51				$ 1.57			$ (0.06)
Balance sheet
Deferred policy acquisition costs	884		817				1,312			(495)
Deferred income taxes, net	533		803				632			171
Other assets, including other intangibles	2,328		1,750				1,776			(26)
All other assets			47,327				47,327			0
Total assets	52,785		50,697				51,047			(350)
Net translation foreign currencies	38		3				(3)			6
Retained earnings	11,123		10,787				11,143			(356)
Other Shareholders Equity			(2,796)				(2,796)			0
Total shareholders' equity	8,561		7,994				8,344			(350)
Statement of Cash Flows
Net Income	371	414				430			(16)
Deferred income taxes	46	143				148			(5)
Deferred policy acquisition costs	(47)	(48)				(67)			19
Other assets	155	41				39			2
Segment information:
Premiums and fees, Mail order pharmacy revenues and Other revenues				875	704			706			(2)
Segment earnings				$ 80	$ 61			$ 77			$ (16)