Quarterly report pursuant to Section 13 or 15(d)

Activity in Accumulated Other Comprehensive Income (Loss) (Phantoms) (Detail)

v3.8.0.1
Activity in Accumulated Other Comprehensive Income (Loss) (Phantoms) (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance at beginning of period $ (4,867)      
Change in foreign currency translation adjustment, net of tax (6) $ 30    
Balance at end of period (5,638) (4,462)    
Foreign currency translation gain (loss):        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance at beginning of period (930) (1,016)    
Change in foreign currency translation adjustment, net of tax (6) 30    
Reclassification to retained earnings pursuant to the early adoption of ASU 2018-02     $ (47) $ 0
Balance at end of period (983) (986)    
Aggregate adjustment for the period, tax (9) (14)    
Unrealized gain (loss) on marketable securities, net of tax:        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance at beginning of period (2) (1)    
Balance at end of period (5) (1)    
Current period changes in fair value, tax effect (1) 0    
Reclassification to earnings, tax effect 0 0    
Unrealized gain (loss) on cash flow hedges, net of tax:        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance at beginning of period (366) (45)    
Reclassification to retained earnings pursuant to the early adoption of ASU 2018-02     (79) 0
Balance at end of period (511) (86)    
Current period changes in fair value, tax effect (33) (17)    
Reclassification to earnings, tax effect 12 (7)    
Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Balance at beginning of period (3,569) (3,421)    
Reclassification to retained earnings pursuant to the early adoption of ASU 2018-02     $ (609) $ 0
Balance at end of period (4,139) (3,389)    
Reclassification to earnings, tax effect 12 18    
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax $ 0 $ 0