Consolidated Statements Of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Premiums									$ 45,959	$ 38,829	$ 37,009
Services									2,164	2,109	1,726
Investment income									377	375	391
Total revenues	12,328	12,238	12,222	11,712	10,187	10,319	10,321	10,486	48,500	41,313	39,126
Operating expenses:
Benefits									38,166	32,564	30,985
Operating costs									7,639	6,355	5,830
Depreciation and amortization									333	333	295
Total operating expenses									46,138	39,252	37,110
Income from operations									2,362	2,061	2,016
Interest expense									192	140	105
Income before income taxes	287	551	646	686	(49)	586	654	730	2,170	1,921	1,911
Provision for income taxes									1,023	690	689
Net income	$ 145	$ 290	$ 344	$ 368	$ (30)	$ 368	$ 420	$ 473	$ 1,147	$ 1,231	$ 1,222
Basic earnings per common share (in dollars per share)	$ 0.96	$ 1.87	$ 2.22	$ 2.37	$ (0.19)	$ 2.34	$ 2.66	$ 2.97	$ 7.44	$ 7.81	$ 7.56
Diluted earnings per common share (in dollars per share)	$ 0.94	$ 1.85	$ 2.19	$ 2.35	$ (0.19)	$ 2.31	$ 2.63	$ 2.95	$ 7.36	$ 7.73	$ 7.47
Dividends declared per common share (in dollars per share)									$ 1.11	$ 1.07	$ 1.03