Schedule I Schedule I Condensed Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities
Cash flows from operating activities	$ 6,968	$ 6,273	$ 5,625
Investing activities
Cash paid for acquisitions	(1,844)	(2,323)	(486)
Cash received from dispositions, net of cash transferred	385	19	0
Cash flows used for investing activities	(4,172)	(5,339)	(976)
Financing activities
Common stock repurchases	(2,994)	(2,517)	(1,801)
Proceeds from common stock issuances	381	272	282
Dividends paid	(651)	(449)	(36)
(Repayments of) proceeds from commercial paper, net	(933)	930	(99)
Proceeds from issuance of long-term debt	2,234	747	0
Repayments of long-term debt	(955)	(1,583)	(1,350)
Interest rate swap termination	132	0	513
Other	53	20	(10)
Cash flows used for financing activities	(2,490)	(1,611)	(2,275)
Increase (decrease) in cash and cash equivalents	306	(677)	2,374
Cash and cash equivalents, beginning of period	9,123	9,800	7,426
Cash and cash equivalents, end of period	9,429	9,123	9,800
Supplemental cash flow disclosures
Cash paid for interest	472	509	527
Cash paid for income taxes	2,739	2,725	2,048
Parent Company [Member]
Operating activities
Cash flows from operating activities	5,560	3,731	5,065
Investing activities
Capital contributions to subsidiaries	(171)	(104)	(90)
Cash paid for acquisitions	(2,081)	(2,470)	(1,045)
Cash flows used for investing activities	(2,252)	(2,574)	(1,135)
Financing activities
Common stock repurchases	(2,994)	(2,517)	(1,801)
Proceeds from common stock issuances	381	272	282
Dividends paid	(651)	(449)	(36)
(Repayments of) proceeds from commercial paper, net	(933)	930	(99)
Proceeds from issuance of long-term debt	2,234	747	0
Repayments of long-term debt	(955)	(1,583)	(1,350)
Interest rate swap termination	132	0	513
Proceeds from issuance of note to subsidiary	15	30	0
Other	53	20	(10)
Cash flows used for financing activities	(2,718)	(2,550)	(2,501)
Increase (decrease) in cash and cash equivalents	590	(1,393)	1,429
Cash and cash equivalents, beginning of period	916	2,309	880
Cash and cash equivalents, end of period	1,506	916	2,309
Supplemental cash flow disclosures
Cash paid for interest	418	459	485
Cash paid for income taxes	$ 2,739	$ 2,725	$ 2,048