Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Cash receipts from customers	$ 43,913	$ 41,482
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(36,178)	(35,575)
Cash paid to other suppliers and employees	(3,823)	(2,934)
Interest received	6	5
Interest paid	(328)	(378)
Income taxes paid	(57)	(161)
Net cash provided by operating activities	3,533	2,439
Cash flows from investing activities:
Purchases of property and equipment	(457)	(598)
Proceeds from sale of property and equipment and other assets	5	2
Acquisitions (net of cash acquired) and other investments	(110)	(51)
Purchase of available-for-sale investments		(36)
Maturity of available-for-sale investments	8	50
Net cash used in investing activities	(554)	(633)
Cash flows from financing activities:
Decrease in short-term debt	(106)
Purchase of noncontrolling interest in subsidiary		(39)
Dividends paid	(516)	(470)
Proceeds from exercise of stock options	121	104
Payments for taxes related to net share settlement of equity awards	(11)	(12)
Repurchase of common stock	(3,621)	(2,066)
Other		(4)
Net cash used in financing activities	(4,133)	(2,487)
Effect of exchange rate changes on cash and cash equivalents		1
Net decrease in cash and cash equivalents	(1,154)	(680)
Cash and cash equivalents at the beginning of the period	3,371	2,459
Cash and cash equivalents at the end of the period	2,217	1,779
Reconciliation of net income to net cash provided by operating activities:
Net income	953	1,147
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	619	617
Stock-based compensation	55	57
Deferred income taxes and other noncash items	14	17
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	48	(1,131)
Inventories	456	89
Other current assets	(74)	106
Other assets	(1)	(52)
Accounts payable and claims and discounts payable	(539)	798
Accrued expenses	1,848	768
Other long-term liabilities	154	23
Net cash provided by operating activities	$ 3,533	$ 2,439