Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Cash receipts from customers	$ 264,327,000,000	$ 248,393,000,000	$ 186,519,000,000
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(158,636,000,000)	(149,655,000,000)	(148,981,000,000)
Insurance benefits paid	(55,124,000,000)	(52,242,000,000)	(6,897,000,000)
Cash paid to other suppliers and employees	(29,763,000,000)	(28,932,000,000)	(17,234,000,000)
Interest and investment income received	894,000,000	955,000,000	644,000,000
Interest paid	(2,904,000,000)	(2,954,000,000)	(2,803,000,000)
Income taxes paid	(2,929,000,000)	(2,717,000,000)	(2,383,000,000)
Net cash provided by operating activities	15,865,000,000	12,848,000,000	8,865,000,000
Cash flows from investing activities:
Proceeds from sales and maturities of investments	6,467,000,000	7,049,000,000	817,000,000
Purchases of investments	(9,639,000,000)	(7,534,000,000)	(692,000,000)
Purchases of property and equipment	(2,437,000,000)	(2,457,000,000)	(2,037,000,000)
Proceeds from sale-leaseback transactions	101,000,000	5,000,000	0
Acquisitions (net of cash acquired)	(866,000,000)	(444,000,000)	(42,226,000,000)
Proceeds from sale of subsidiaries and other assets	840,000,000	0	832,000,000
Other	0	42,000,000	21,000,000
Net cash used in investing activities	(5,534,000,000)	(3,339,000,000)	(43,285,000,000)
Cash flows from financing activities:
Net repayments of short-term debt	0	(720,000,000)	(556,000,000)
Proceeds from issuance of long-term debt	9,958,000,000	3,736,000,000	44,343,000,000
Repayments of long-term debt	(15,631,000,000)	(8,336,000,000)	(5,522,000,000)
Derivative settlements	(7,000,000)	(25,000,000)	446,000,000
Dividends paid	(2,624,000,000)	(2,603,000,000)	(2,038,000,000)
Proceeds from exercise of stock options	264,000,000	210,000,000	242,000,000
Payments for taxes related to net share settlement of equity awards	(88,000,000)	(112,000,000)	(97,000,000)
Other	(27,000,000)	0	1,000,000
Net cash provided by (used in) financing activities	(8,155,000,000)	(7,850,000,000)	36,819,000,000
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0	0	(4,000,000)
Net increase in cash, cash equivalents and restricted cash	2,176,000,000	1,659,000,000	2,395,000,000
Cash, cash equivalents and restricted cash at the beginning of the period	5,954,000,000	4,295,000,000	1,900,000,000
Cash, cash equivalents and restricted cash at the end of the period	8,130,000,000	5,954,000,000	4,295,000,000
Reconciliation of net income (loss) to net cash provided by operating activities:
Net income (loss)	7,192,000,000	6,631,000,000	(596,000,000)
Reconciliation of net income (loss) to net cash provided by operating activities:
Depreciation and amortization	4,441,000,000	4,371,000,000	2,718,000,000
Goodwill impairments	0	0	6,149,000,000
Stock-based compensation	400,000,000	453,000,000	280,000,000
(Gain) loss on sale of subsidiaries	(269,000,000)	205,000,000	86,000,000
Loss on early extinguishment of debt	1,440,000,000	79,000,000	0
Deferred income taxes	(570,000,000)	(654,000,000)	87,000,000
Other noncash items	72,000,000	264,000,000	253,000,000
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(1,510,000,000)	(2,158,000,000)	(1,139,000,000)
Inventories	(973,000,000)	(1,075,000,000)	(1,153,000,000)
Other assets	364,000,000	(614,000,000)	(3,000,000)
Accounts payable and pharmacy claims and discounts payable	2,769,000,000	3,550,000,000	2,329,000,000
Health care costs payable and other insurance liabilities	(231,000,000)	320,000,000	(311,000,000)
Other liabilities	2,740,000,000	1,476,000,000	165,000,000
Net cash provided by operating activities	$ 15,865,000,000	$ 12,848,000,000	$ 8,865,000,000