Condensed Consolidating Financial Statements - Condensed Consolidating Statements Of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	$ 3,106	$ 2,687	$ 3,238
Cash flows from investing activities:
Business acquisitions, net of cash acquired	(1)	(444)	(1,560)
Purchases of held-to-maturity securities	0	(260)	(459)
Maturities of held-to-maturity securities	0	224	441
Capital expenditures	440	450	458
Purchases of available-for-sale securities	(135)	(252)	(373)
Other, net	73	238	435
Net cash used by investing activities	(367)	(656)	(1,974)
Cash flows from financing activities:
Proceeds from fixed-rate notes	0	2,382	1,497
Purchases of common stock	(740)	(602)	(1,468)
Repayment of fixed-rate notes		(2,400)	(750)
Dividends paid	(591)	(893)	(673)
Proceeds from option exercises	583	146	198
Other, net	23	131	193
Net cash used by financing activities	(725)	(1,382)	(1,201)
Net cash used by discontinued operations	(9)	(2)	(27)
Cash sweep/funding by parent	0	0	0
Net increase in cash and equivalents	2,005	647	36
Cash and equivalents at beginning of year	3,296	2,649	2,613
Cash and equivalents at end of year	5,301	3,296	2,649
Parent
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	(454)	(541)	(359)
Cash flows from investing activities:
Business acquisitions, net of cash acquired		(121)	(233)
Purchases of held-to-maturity securities			(459)
Maturities of held-to-maturity securities			334
Capital expenditures	1	2	6
Purchases of available-for-sale securities			(274)
Other, net	3	221	246
Net cash used by investing activities	2	98	(392)
Cash flows from financing activities:
Proceeds from fixed-rate notes		2,382	1,497
Purchases of common stock	(740)	(602)	(1,468)
Repayment of fixed-rate notes		(2,400)	(750)
Dividends paid	(591)	(893)	(673)
Proceeds from option exercises	583
Other, net	23	154	216
Net cash used by financing activities	(725)	(1,359)	(1,178)
Net cash used by discontinued operations	(9)	(2)	(27)
Cash sweep/funding by parent	3,113	2,522	1,878
Net increase in cash and equivalents	1,927	718	(78)
Cash and equivalents at beginning of year	2,248	1,530	1,608
Cash and equivalents at end of year	4,175	2,248	1,530
Guarantors on a Combined Basis
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	2,810	2,850	3,524
Cash flows from investing activities:
Business acquisitions, net of cash acquired		(297)	(1,327)
Purchases of held-to-maturity securities			0
Maturities of held-to-maturity securities			0
Capital expenditures	381	390	381
Purchases of available-for-sale securities			(99)
Other, net	59	(1)	192
Net cash used by investing activities	(322)	(688)	(1,615)
Cash flows from financing activities:
Proceeds from fixed-rate notes		0	0
Purchases of common stock	0	0	0
Repayment of fixed-rate notes		0	0
Dividends paid	0	0	0
Proceeds from option exercises	0
Other, net	0	(21)	(20)
Net cash used by financing activities	0	(21)	(20)
Net cash used by discontinued operations	0	0	0
Cash sweep/funding by parent	(2,488)	(2,141)	(1,889)
Net increase in cash and equivalents	0	0	0
Cash and equivalents at beginning of year	0	0	0
Cash and equivalents at end of year	0	0	0
Other Subsidiaries on a Combined Basis
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	750	378	73
Cash flows from investing activities:
Business acquisitions, net of cash acquired		(26)	0
Purchases of held-to-maturity securities			0
Maturities of held-to-maturity securities			107
Capital expenditures	58	58	71
Purchases of available-for-sale securities			0
Other, net	11	18	(3)
Net cash used by investing activities	(47)	(66)	33
Cash flows from financing activities:
Proceeds from fixed-rate notes		0	0
Purchases of common stock	0	0	0
Repayment of fixed-rate notes		0	0
Dividends paid	0	0	0
Proceeds from option exercises	0
Other, net	0	(2)	(3)
Net cash used by financing activities	0	(2)	(3)
Net cash used by discontinued operations	0	0	0
Cash sweep/funding by parent	(625)	(381)	11
Net increase in cash and equivalents	78	(71)	114
Cash and equivalents at beginning of year	1,048	1,119	1,005
Cash and equivalents at end of year	1,126	1,048	1,119
Consolidating Adjustments
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	0	0	0
Cash flows from investing activities:
Business acquisitions, net of cash acquired		0	0
Purchases of held-to-maturity securities			0
Maturities of held-to-maturity securities			0
Capital expenditures	0	0	0
Purchases of available-for-sale securities			0
Other, net	0	0	0
Net cash used by investing activities	0	0	0
Cash flows from financing activities:
Proceeds from fixed-rate notes		0	0
Purchases of common stock	0	0	0
Repayment of fixed-rate notes		0	0
Dividends paid	0	0	0
Proceeds from option exercises	0
Other, net	0	0	0
Net cash used by financing activities	0	0	0
Net cash used by discontinued operations	0	0	0
Cash sweep/funding by parent	0	0	0
Net increase in cash and equivalents	0	0	0
Cash and equivalents at beginning of year	0	0	0
Cash and equivalents at end of year	$ 0	$ 0	$ 0