Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Cash receipts from customers	$ 56,446	$ 57,644
Cash paid for inventory and prescriptions dispensed by retail network pharmacies	(44,657)	(45,289)
Cash paid to other suppliers and employees	(7,452)	(7,134)
Interest received	2	1
Interest paid	(267)	(281)
Income taxes paid	(1,530)	(924)
Net cash provided by operating activities	2,542	4,017
Cash flows from investing activities:
Purchases of property and equipment	(804)	(818)
Proceeds from sale of property and equipment	11	0
Acquisitions (net of cash acquired) and other investments	(300)	(274)
Proceeds from sale of subsidiary	0	7
Net cash used in investing activities	(1,093)	(1,085)
Cash flows from financing activities:
Decrease in short-term debt	(690)	(550)
Repayments of long-term debt	0	(54)
Purchase of noncontrolling interest in subsidiary	0	(26)
Dividends paid	(553)	(420)
Proceeds from exercise of stock options	309	518
Excess tax benefits from stock-based compensation	34	8
Repurchase of common stock	(748)	(1,998)
Net cash used in financing activities	(1,648)	(2,522)
Effect of Exchange Rate on Cash and Cash Equivalents	(2)	0
Net increase (decrease) in cash and cash equivalents	(201)	410
Cash and cash equivalents at beginning of period	1,375	1,413
Cash and cash equivalents at end of period	1,174	1,823
Reconciliation of net income to net cash provided by operating activities:
Net income	2,077	1,740
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	951	854
Stock-based compensation	66	64
Deferred income taxes and other noncash items	82	83
Change in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(575)	(13)
Inventories	204	(527)
Other current assets	165	254
Other assets	(138)	(181)
Accounts payable and claims and discounts payable	98	655
Accrued expenses	(412)	1,095
Other long-term liabilities	24	(7)
Net cash provided by operating activities	$ 2,542	$ 4,017