Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Cash receipts from customers	$ 30,505	$ 28,018
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(23,966)	(22,270)
Cash paid to other suppliers and employees	(4,196)	(3,889)
Interest received	3	1
Interest paid	(104)	(104)
Income taxes paid	(70)	(116)
Net cash provided by operating activities	2,172	1,640
Cash flows from investing activities:
Purchases of property and equipment	(388)	(318)
Proceeds from sale-leaseback transactions	5	0
Proceeds from sale of property and equipment	5	5
Acquisitions (net of cash acquired) and other investments	(2,194)	(254)
Purchase of available-for-sale investments	43	0
Sales/maturities of available-for-sale investments	55	0
Net cash used in investing activities	(2,560)	(567)
Cash flows from financing activities:
Decrease in short-term debt	0	(390)
Dividends paid	(325)	(277)
Proceeds from exercise of stock options	154	150
Excess tax benefits from stock-based compensation	37	13
Repurchase of common stock	(801)	(393)
Net cash used in financing activities	(935)	(897)
Net increase (decrease) in cash and cash equivalents	(1,323)	176
Cash and cash equivalents at beginning of period	4,089	1,375
Cash and cash equivalents at end of period	2,766	1,551
Reconciliation of net income to net cash provided by operating activities:
Net income	1,129	954
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	477	502
Stock-based compensation	35	34
Deferred income taxes and other noncash items	16	66
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(139)	(113)
Inventories	(64)	186
Other current assets	(70)	(238)
Other assets	(39)	(135)
Accounts payable and claims and discounts payable	339	(230)
Accrued expenses	362	114
Other long-term liabilities	(14)	24
Net cash provided by operating activities	$ 2,172	$ 1,640