Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Cash receipts from customers	$ 87,977,000,000	$ 88,343,000,000
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(72,500,000,000)	(73,748,000,000)
Cash paid to other suppliers and employees	(8,471,000,000)	(7,000,000,000)
Interest received	194,000,000	10,000,000
Interest paid	(560,000,000)	(539,000,000)
Income taxes paid	(1,351,000,000)	(1,534,000,000)
Net cash provided by operating activities	5,289,000,000	5,532,000,000
Cash flows from investing activities:
Purchases of property and equipment	(912,000,000)	(888,000,000)
Proceeds from sale of property and equipment and other assets	7,000,000	13,000,000
Acquisitions (net of cash acquired) and other investments	(573,000,000)	(275,000,000)
Purchase of available-for-sale investments	(36,000,000)
Maturity of available-for-sale investments	37,000,000	16,000,000
Proceeds from sale of subsidiary	725,000,000
Net cash used in investing activities	(752,000,000)	(1,134,000,000)
Cash flows from financing activities:
Decrease in short-term debt	(1,276,000,000)	(774,000,000)
Proceeds from issuance of long-term debt	39,376,000,000
Repayments of long-term debt	(1,000,000)
Derivative settlements	446,000,000
Repurchase of common stock		(3,961,000,000)
Dividends paid	(1,018,000,000)	(1,028,000,000)
Proceeds from exercise of stock options	130,000,000	189,000,000
Payments for taxes related to net share settlement of equity awards	(37,000,000)	(60,000,000)
Other		(1,000,000)
Net cash provided by (used in) financing activities	37,620,000,000	(5,635,000,000)
Net increase (decrease) in cash, cash equivalents and restricted cash	42,157,000,000	(1,237,000,000)
Cash, cash equivalents and restricted cash at the beginning of the period	1,900,000,000	3,520,000,000
Cash, cash equivalents and restricted cash at the end of the period	44,057,000,000	2,283,000,000
Reconciliation of net income (loss) to net cash provided by operating activities:
Net income (loss)	(1,565,000,000)	2,051,000,000
Adjustments required to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	1,291,000,000	1,242,000,000
Goodwill impairments	3,921,000,000	135,000,000
Stock-based compensation	110,000,000	108,000,000
Deferred income taxes and other noncash items	252,000,000	21,000,000
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(1,059,000,000)	(114,000,000)
Inventories	369,000,000	492,000,000
Other current assets	(45,000,000)	(31,000,000)
Other assets	(129,000,000)	(38,000,000)
Accounts payable and claims and discounts payable	1,045,000,000	180,000,000
Accrued expenses	1,143,000,000	1,345,000,000
Other long-term liabilities	(44,000,000)	141,000,000
Net cash provided by operating activities	$ 5,289,000,000	$ 5,532,000,000