Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Cash receipts from customers	$ 57,644	$ 47,950
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(45,289)	(37,307)
Cash paid to other suppliers and employees	(7,134)	(6,149)
Interest received	1	2
Interest paid	(281)	(298)
Income taxes paid	(924)	(1,125)
Net cash provided by operating activities	4,017	3,073
Cash flows from investing activities:
Purchases of property and equipment	(818)	(710)
Proceeds from sale-leaseback transactions		11
Acquisitions (net of cash acquired) and other investments	(274)	(1,366)
Purchase of available-for-sale investments		(2)
Maturity of available-for-sale investments		1
Proceeds from sale of subsidiary	7
Net cash used in investing activities	(1,085)	(2,066)
Cash flows from financing activities:
Decrease in short-term debt	(550)	(300)
Proceeds from issuance of long-term debt		1,463
Repayments of long-term debt	(54)	(302)
Purchase of noncontrolling interest in subsidiary	(26)
Dividends paid	(420)	(341)
Derivative settlements		(19)
Proceeds from exercise of stock options	518	264
Excess tax benefits from stock-based compensation	8
Repurchase of common stock	(1,998)	(971)
Net cash used in financing activities	(2,522)	(206)
Net increase in cash and cash equivalents	410	801
Cash and cash equivalents at beginning of period	1,413	1,427
Cash and cash equivalents at end of period	1,823	2,228
Reconciliation of net income to net cash provided by operating activities:
Net income	1,740	1,527
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	854	765
Stock-based compensation	64	65
Deferred income taxes and other noncash items	83	129
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(13)	(472)
Inventories	(527)	584
Other current assets	254	(164)
Other assets	(181)	(62)
Accounts payable	655	722
Accrued expenses	1,095	54
Other long-term liabilities	(7)	(75)
Net cash provided by operating activities	$ 4,017	$ 3,073