Condensed Consolidating Financial Statements - Condensed Consolidating Statements Of Cash Flows (Detail) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Jan. 24, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities			$ 2,499	$ 3,728	$ 3,111
Cash flows from investing activities:
Capital expenditures			(569)	(521)	(436)
Maturities of held-to-maturity securities			500	0	0
Proceeds from sales of assets			291	102	104
Purchases of held-to-maturity securities			0	(500)	0
Net cash provided (used) by investing activities			200	(1,102)	(363)
Cash flows from financing activities:
Purchases of common stock		$ (3,400)	(3,233)	(3,382)	(740)
Dividends paid			(873)	(822)	(591)
Repayments of fixed-rate notes			(500)	0	0
Proceeds from stock option exercises			268	547	583
Net cash used by financing activities			(4,259)	(3,575)	(725)
Net cash (used) provided by discontinued operations			(43)	36	(18)
Net (decrease) increase in cash and equivalents			(1,603)	(913)	2,005
Cash and equivalents at beginning of year		5,301	4,388	5,301	3,296
Cash and equivalents at end of year			2,785	4,388	5,301
Parent
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	[1]		(58)	(296)	(454)
Cash flows from investing activities:
Capital expenditures			(42)	(71)	(1)
Maturities of held-to-maturity securities			500
Proceeds from sales of assets			162
Purchases of held-to-maturity securities				(500)
Other, net			4	3	3
Net cash provided (used) by investing activities			624	(568)	2
Cash flows from financing activities:
Purchases of common stock			(3,233)	(3,382)	(740)
Dividends paid			(873)	(822)	(591)
Repayments of fixed-rate notes			(500)
Proceeds from stock option exercises			268	547	583
Other, net			77	83	23
Net cash used by financing activities			(4,261)	(3,574)	(725)
Net cash (used) provided by discontinued operations			(43)	36	(18)
Cash sweep/funding by parent			2,934	2,759	3,074
Net (decrease) increase in cash and equivalents			(804)	(1,643)	1,879
Cash and equivalents at beginning of year		4,179	2,536	4,179	2,300
Cash and equivalents at end of year			1,732	2,536	4,179
Guarantors on a Combined Basis
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	[1]		2,202	2,798	2,810
Cash flows from investing activities:
Capital expenditures			(475)	(409)	(381)
Maturities of held-to-maturity securities			0
Proceeds from sales of assets			129
Purchases of held-to-maturity securities				0
Other, net			(26)	(74)	59
Net cash provided (used) by investing activities			(372)	(483)	(322)
Cash flows from financing activities:
Purchases of common stock			0	0	0
Dividends paid			0	0	0
Repayments of fixed-rate notes			0
Proceeds from stock option exercises			0	0	0
Other, net			2	(1)	0
Net cash used by financing activities			2	(1)	0
Net cash (used) provided by discontinued operations			0	0	0
Cash sweep/funding by parent			(1,832)	(2,314)	(2,488)
Net (decrease) increase in cash and equivalents			0	0	0
Cash and equivalents at beginning of year		0	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	[1]		355	1,226	755
Cash flows from investing activities:
Capital expenditures			(52)	(41)	(54)
Maturities of held-to-maturity securities			0
Proceeds from sales of assets			0
Purchases of held-to-maturity securities				0
Other, net			0	(10)	11
Net cash provided (used) by investing activities			(52)	(51)	(43)
Cash flows from financing activities:
Purchases of common stock			0	0	0
Dividends paid			0	0	0
Repayments of fixed-rate notes			0
Proceeds from stock option exercises			0	0	0
Other, net			0	0	0
Net cash used by financing activities			0	0	0
Net cash (used) provided by discontinued operations			0	0	0
Cash sweep/funding by parent			(1,102)	(445)	(586)
Net (decrease) increase in cash and equivalents			(799)	730	126
Cash and equivalents at beginning of year		1,122	1,852	1,122	996
Cash and equivalents at end of year			1,053	1,852	1,122
Consolidating Adjustments
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	[1]		0	0	0
Cash flows from investing activities:
Capital expenditures			0	0	0
Maturities of held-to-maturity securities			0
Proceeds from sales of assets			0
Purchases of held-to-maturity securities				0
Other, net			0	0	0
Net cash provided (used) by investing activities			0	0	0
Cash flows from financing activities:
Purchases of common stock			0	0	0
Dividends paid			0	0	0
Repayments of fixed-rate notes			0
Proceeds from stock option exercises			0	0	0
Other, net			0	0	0
Net cash used by financing activities			0	0	0
Net cash (used) provided by discontinued operations			0	0	0
Cash sweep/funding by parent			0	0	0
Net (decrease) increase in cash and equivalents			0	0	0
Cash and equivalents at beginning of year		0	0	0	0
Cash and equivalents at end of year			0	0	0
Total Consolidated
Condensed Consolidating Financial Information [Line Items]
Net cash provided by operating activities	[1]		2,499	3,728	3,111
Cash flows from investing activities:
Capital expenditures			(569)	(521)	(436)
Maturities of held-to-maturity securities			500
Proceeds from sales of assets			291
Purchases of held-to-maturity securities				(500)
Other, net			(22)	(81)	73
Net cash provided (used) by investing activities			200	(1,102)	(363)
Cash flows from financing activities:
Purchases of common stock			(3,233)	(3,382)	(740)
Dividends paid			(873)	(822)	(591)
Repayments of fixed-rate notes			(500)
Proceeds from stock option exercises			268	547	583
Other, net			79	82	23
Net cash used by financing activities			(4,259)	(3,575)	(725)
Net cash (used) provided by discontinued operations			(43)	36	(18)
Cash sweep/funding by parent			0	0	0
Net (decrease) increase in cash and equivalents			(1,603)	(913)	2,005
Cash and equivalents at beginning of year		$ 5,301	4,388	5,301	3,296
Cash and equivalents at end of year			$ 2,785	$ 4,388	$ 5,301

[1] * Continuing operations only.