Activity in Accumulated Other Comprehensive Income (Loss) (Phantoms) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (4,202)	$ (3,606)	$ (4,202)	$ (3,606)	$ (4,483)
Change in foreign currency translation adjustment, net of tax	24	(31)	54	(5)
Foreign currency translation gain (loss):
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(962)	(902)	(962)	(902)	(1,016)	$ (897)
Change in foreign currency translation adjustment, net of tax			54	(5)
Aggregate adjustment for the period, tax			(93)	0
Unrealized gain (loss) on marketable securities, net of tax:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	0	4	0	4	(1)	(1)
Current period changes in fair value, tax effect			0	4
Reclassification to earnings, tax effect			0	0
Unrealized gain (loss) on cash flow hedges, net of tax:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(237)	(52)	(237)	(52)	(45)	67
Current period changes in fair value, tax effect			(109)	(5)
Reclassification to earnings, tax effect			(7)	(67)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (3,003)	$ (2,656)	(3,003)	(2,656)	$ (3,421)	$ (2,709)
Reclassification to earnings, tax effect			37	33
Other Comprehensive Income (Loss), Finalization of Pension and Other Postretirement Benefit Plan Valuation, Tax			$ 214	$ 0