Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net earnings	$ 10,823	$ 7,073	$ 5,868
Noncash items:
Depreciation and amortization	2,245	2,055	1,693
Deferred income taxes	(965)	81	(73)
Share-based compensation	597	485	406
Other, net	217	(82)	(235)
Net change in other operating items, net of effects from acquisitions and changes in AARP balances:
Accounts receivable	(1,062)	(1,357)	(591)
Other assets	(630)	(1,601)	(1,430)
Medical costs payable	1,284	1,849	2,585
Accounts payable and other liabilities	930	1,494	1,280
Unearned revenues	157	(202)	237
Cash flows from operating activities	13,596	9,795	9,740
Investing activities
Purchases of investments	(14,588)	(17,547)	(9,939)
Sales of investments	4,623	7,339	6,054
Maturities of investments	5,646	4,281	3,354
Cash paid for acquisitions, net of cash assumed	(2,131)	(1,760)	(16,164)
Purchases of property, equipment and capitalized software	(2,023)	(1,705)	(1,556)
Other, net	(126)	37	(144)
Cash flows used for investing activities	(8,599)	(9,355)	(18,395)
Financing activities
Common share repurchases	(1,500)	(1,280)	(1,200)
Cash dividends paid	(2,773)	(2,261)	(1,786)
Proceeds from common stock issuances	688	429	402
Repayments of long-term debt	(4,398)	(2,596)	(1,041)
(Repayments of) proceeds from commercial paper, net	(3,508)	(382)	3,666
Proceeds from issuance of long-term debt	5,291	3,968	11,982
Customer funds administered	3,172	1,692	768
Other, net	(413)	(581)	(552)
Cash flows (used for) from financing activities	(3,441)	(1,011)	12,239
Effect of exchange rate changes on cash and cash equivalents	(5)	78	(156)
Increase (decrease) in cash and cash equivalents	1,551	(493)	3,428
Cash and cash equivalents, beginning of period	10,430	10,923	7,495
Cash and cash equivalents, end of period	11,981	10,430	10,923
Supplemental cash flow disclosures
Cash paid for interest	1,133	1,055	639
Cash paid for income taxes	4,004	4,726	4,401
Supplemental schedule of non-cash investing activities
Common stock issued for acquisitions	$ 2,164	$ 0	$ 0