Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Premiums									$ 62,948	$ 54,941	$ 52,380
Services									1,439	1,457	982
Investment income									501	514	405
Total revenues	$ 16,295	$ 16,241	$ 16,245	$ 16,107	$ 14,168	$ 14,206	$ 14,259	$ 14,279	64,888	56,912	53,767
Operating expenses:
Benefits									53,857	45,882	43,496
Operating costs									7,381	7,525	6,567
Merger termination fee and related costs, net									0	0	(936)
Depreciation and amortization									458	405	378
Total operating expenses									61,696	53,812	49,505
Income from operations									3,192	3,100	4,262
Loss on sale of business									0	786	0
Interest expense									242	218	242
Other (income) expense, net									(506)	33	0
Income before income taxes and equity in net earnings	593	888	1,229	746	436	901	19	707	3,456	2,063	4,020
Provision for income taxes									763	391	1,572
Equity in net earnings of Kindred at Home									14	11	0
Net income	$ 512	$ 689	$ 940	$ 566	$ 355	$ 644	$ 193	$ 491	$ 2,707	$ 1,683	$ 2,448
Basic earnings per common share (in USD per share)	$ 3.87	$ 5.16	$ 6.96	$ 4.18	$ 2.60	$ 4.68	$ 1.40	$ 3.56	$ 20.20	$ 12.24	$ 16.94
Diluted earnings per common share (in USD per share)	$ 3.84	$ 5.14	$ 6.94	$ 4.16	$ 2.58	$ 4.65	$ 1.39	$ 3.53	$ 20.10	$ 12.16	$ 16.81