Condensed Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues:
Premiums	$ 9,701	$ 9,166	$ 19,569	$ 18,941
Services	528	434	1,053	784
Investment income	92	99	185	193
Total revenues	10,321	9,699	20,807	19,918
Operating expenses:
Benefits	8,091	7,652	16,286	16,002
Operating costs	1,461	1,384	2,907	2,767
Depreciation and amortization	80	73	160	143
Total operating expenses	9,632	9,109	19,353	18,912
Income from operations	689	590	1,454	1,006
Interest expense	35	26	70	52
Income before income taxes	654	564	1,384	954
Provision for income taxes	234	208	491	350
Net income	$ 420	$ 356	$ 893	$ 604
Basic earnings per common share	$ 2.66	$ 2.19	$ 5.64	$ 3.70
Diluted earnings per common share	$ 2.63	$ 2.16	$ 5.58	$ 3.65
Dividends declared per common share	$ 0.27	$ 0.26	$ 0.53	$ 0.51