Schedule I Condensed Cash Flow (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Cash flows from operating activities	$ 6,991	$ 7,155	$ 6,968
Investing activities
Cash paid for acquisitions	(362)	(6,280)	(1,844)
Cash flows used for investing activities	(3,089)	(8,649)	(4,172)
Financing activities
Common stock repurchases	(3,170)	(3,084)	(2,994)
Proceeds from common stock issuances	598	1,078	381
Cash dividends paid	(1,056)	(820)	(651)
(Repayments of) proceeds from commercial paper, net	(474)	1,587	(933)
Proceeds from issuance of long-term debt	2,235	3,966	2,234
Repayments of long-term debt	(1,609)	(986)	(955)
Interest rate swap termination	0	0	(132)
Other, net	(27)	(627)	259
Cash flows used for financing activities	(4,946)	471	(2,490)
(Decrease) increase in cash and cash equivalents	(1,130)	(1,023)	306
Cash and cash equivalents, beginning of period	8,406	9,429	9,123
Cash and Cash Equivalents, end of period	7,276	8,406	9,429
Supplemental cash flow disclosures
Cash paid for interest	724	600	472
Cash paid for income taxes	2,785	2,666	2,739
Parent [Member]
Operating activities
Cash flows from operating activities	5,099	6,116	5,560
Investing activities
Issuance of notes to subsidiaries	(1,517)	(4,149)	0
Repayments of notes receivable from subsidiaries	275	0	0
Cash paid for acquisitions	(274)	(3,737)	(2,081)
Capital contributions to subsidiaries	(942)	(99)	(171)
Cash flows used for investing activities	(2,458)	(7,985)	(2,252)
Financing activities
Common stock repurchases	(3,170)	(3,084)	(2,994)
Proceeds from common stock issuances	598	1,078	381
Cash dividends paid	(1,056)	(820)	(651)
(Repayments of) proceeds from commercial paper, net	(474)	1,587	(933)
Proceeds from issuance of long-term debt	2,235	3,966	2,234
Repayments of long-term debt	(943)	(986)	(955)
Interest rate swap termination	0	0	132
Proceeds of note from subsidiary	40	30	15
Other, net	(74)	(383)	53
Cash flows used for financing activities	(2,844)	1,388	(2,718)
(Decrease) increase in cash and cash equivalents	(203)	(481)	590
Cash and cash equivalents, beginning of period	1,025	1,506	916
Cash and Cash Equivalents, end of period	822	1,025	1,506
Supplemental cash flow disclosures
Cash paid for interest	618	547	418
Cash paid for income taxes	$ 2,765	$ 2,666	$ 2,739