Schedule Summarizing Quarterly Operation Results (Schedule Summarizing Quarterly Operation Results) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010		Sep. 30, 2010	Jun. 30, 2010		Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Financial Information [Abstract]
Total revenues	$ 9,056.0	$ 9,301.0	$ 9,284.0	$ 9,191.0	$ 8,276.0	[1]	$ 8,351.0	$ 8,589.0	[2]	$ 8,380.0	$ 36,832.0	$ 33,596.0	$ 30,743.0
Income before income taxes	313	699	726	497	174	[1]	622	536	[2]	417	2,235	1,749	1,602
Net income	199	445	460	315	107	[1]	393	340	[2]	259	1,419	1,099	1,040
Basic earnings per common share	$ 1.22	$ 2.71	$ 2.76	$ 1.88	$ 0.64	[1]	$ 2.35	$ 2.02	[2]	$ 1.54	$ 8.58	$ 6.55	$ 6.21
Diluted earnings per common share	$ 1.20	$ 2.67	$ 2.71	$ 1.86	$ 0.63	[1]	$ 2.32	$ 2.00	[2]	$ 1.52	$ 8.46	$ 6.47	$ 6.15
Write-down of deferred acquisition costs								147.0				147.0
Charge related to closed block of long-term care policies					139							139
After tax impact of charge					$ 88			$ 93
Impact on EPS of charge					$ 0.52			$ 0.55

[1] Includes an expense of $139 million ($88 million after tax, or $0.52 per diluted common share) associated with reserve strengthening for our closed block of long-term care policies acquired in connection with the 2007 acquisition of KMG America Corporation as more fully described in Note 17 to the consolidated financial statements.

[2] Includes an expense of $147 million ($93 million after tax, or $0.55 per diluted common share) for the write-down of deferred acquisition costs associated with our individual commercial medical policies as more fully described in Note 17 to the consolidated financial statements.