v3.10.0.1
Derivative Instruments and Hedging Activities (Gains (Losses) on Accounting Hedges and Fair Value Hedges) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Borrowings      
Fair Value Hedges - Hedged Items      
Carrying amount of currently or previously hedged liability $ 102,899    
Basis adjustments included in carrying amount (1,689)    
Investment Securities - AFS      
Fair Value Hedges - Hedged Items      
Carrying amount of currently or previously hedged asset 201    
Fair Value Hedges | Interest Expense | Interest Rate Contracts      
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense      
Gains (losses) recognized in Interest Expense (1,529) $ (1,591) $ (1,738)
Fair Value Hedges | Interest Expense | Borrowings      
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense      
Gains (losses) recognized in Interest Expense 1,511 1,393 1,541
Net Investment Hedges | Foreign Exchange Contracts      
Net Investment Hedges      
Gains (losses) recognized in OCI 295 (365) (1)
Forward points excluded from hedge effectiveness testing - Recognized in Interest income $ 68 $ (20) $ (74)