Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Cash receipts from customers	$ 248,393,000,000	$ 186,519,000,000	$ 176,594,000,000
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(149,655,000,000)	(148,981,000,000)	(146,469,000,000)
Insurance benefits paid	(52,242,000,000)	(6,897,000,000)	(2,810,000,000)
Cash paid to other suppliers and employees	(28,932,000,000)	(17,234,000,000)	(15,348,000,000)
Interest and investment income received	955,000,000	644,000,000	21,000,000
Interest paid	(2,954,000,000)	(2,803,000,000)	(1,072,000,000)
Income taxes paid	(2,717,000,000)	(2,383,000,000)	(2,909,000,000)
Net cash provided by operating activities	12,848,000,000	8,865,000,000	8,007,000,000
Cash flows from investing activities:
Proceeds from sales and maturities of investments	7,049,000,000	817,000,000	61,000,000
Purchases of investments	(7,534,000,000)	(692,000,000)	(137,000,000)
Purchases of property and equipment	(2,457,000,000)	(2,037,000,000)	(1,918,000,000)
Proceeds from sale-leaseback transactions	5,000,000
Proceeds from sale-leaseback transactions		0	265,000,000
Acquisitions (net of cash acquired)	(444,000,000)	(42,226,000,000)	(1,181,000,000)
Proceeds from sale of subsidiary and other assets	0	832,000,000	0
Other	42,000,000	21,000,000	33,000,000
Net cash used in investing activities	(3,339,000,000)	(43,285,000,000)	(2,877,000,000)
Cash flows from financing activities:
Net repayments of short-term debt	(720,000,000)	(556,000,000)	(598,000,000)
Proceeds from issuance of long-term debt	3,736,000,000	44,343,000,000	0
Repayments of long-term debt	(8,336,000,000)	(5,522,000,000)	0
Derivative settlements	(25,000,000)	446,000,000	0
Repurchase of common stock	0	0	(4,361,000,000)
Dividends paid	(2,603,000,000)	(2,038,000,000)	(2,049,000,000)
Proceeds from exercise of stock options	210,000,000	242,000,000	329,000,000
Payments for taxes related to net share settlement of equity awards	(112,000,000)	(97,000,000)	(71,000,000)
Other	0	1,000,000	(1,000,000)
Net cash provided by (used in) financing activities	(7,850,000,000)	36,819,000,000	(6,751,000,000)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	(4,000,000)	1,000,000
Net increase (decrease) in cash, cash equivalents and restricted cash	1,659,000,000	2,395,000,000	(1,620,000,000)
Cash, cash equivalents and restricted cash at the beginning of the period	4,295,000,000	1,900,000,000	3,520,000,000
Cash, cash equivalents and restricted cash at the end of the period	5,954,000,000	4,295,000,000	1,900,000,000
Reconciliation of net income (loss) to net cash provided by operating activities:
Net income (loss)	6,631,000,000	(596,000,000)	6,623,000,000
Adjustments required to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	4,371,000,000	2,718,000,000	2,479,000,000
Goodwill impairments	0	6,149,000,000	181,000,000
Loss on settlement of defined benefit pension plans	0	0	187,000,000
Stock-based compensation	453,000,000	280,000,000	234,000,000
Loss on sale of subsidiary	205,000,000	86,000,000	0
Loss on early extinguishment of debt	79,000,000	0	0
Deferred income taxes	(654,000,000)	87,000,000	(1,334,000,000)
Other noncash items	264,000,000	253,000,000	53,000,000
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(2,158,000,000)	(1,139,000,000)	(941,000,000)
Inventories	(1,075,000,000)	(1,153,000,000)	(514,000,000)
Other assets	(614,000,000)	(3,000,000)	(338,000,000)
Accounts payable and pharmacy claims and discounts payable	3,550,000,000	2,329,000,000	1,710,000,000
Health care costs payable and other insurance liabilities	320,000,000	(311,000,000)	0
Other liabilities	$ 1,476,000,000	$ 165,000,000	$ (333,000,000)