Quarterly report pursuant to Section 13 or 15(d)

Amount and Location in the Income Statement for Derivatives Designated as Fair Value Hedges (Detail)

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Amount and Location in the Income Statement for Derivatives Designated as Fair Value Hedges (Detail) - Fair Value Hedging - Interest Expense - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Interest rate contracts        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative Amount of Gain (Loss) Recognized in Income $ (18) $ (59) $ (41) $ 56
Fixed-Rate Debt        
Derivative Instruments, Gain (Loss) [Line Items]        
Hedged Items Amount of Gain (Loss) Recognized in Income $ 18 $ 59 $ 41 $ (56)