Quarterly report pursuant to Section 13 or 15(d)

Amount Recorded in Income Statements for Foreign Currency Forward Contracts Not Designated as Hedges (Detail)

v3.8.0.1
Amount Recorded in Income Statements for Foreign Currency Forward Contracts Not Designated as Hedges (Detail) - Not Designated as Hedging Instrument - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain (Loss) Recognized in Income $ (33) $ (41) $ (9) $ 29
Interest rate contracts | Interest Expense        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain (Loss) Recognized in Income (2) (2) (6) (6)
Foreign exchange contracts | Investment income and other        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain (Loss) Recognized in Income 14 (11) 34 (117)
Investment market price contracts | Investment income and other        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain (Loss) Recognized in Income $ (45) $ (28) $ (37) $ 152