v3.8.0.1
Fair Value of Assets and Liabilities (Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets $ 1,205 $ 1,367
Netting (9,600) (11,716)
Total derivative liabilities 643 345
Netting (5,312) (5,945)
Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 8,424 9,330
Total derivative liabilities 3,804 4,518
Currency    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 165 375
Total derivative liabilities 262 893
Credit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 21 1
Total derivative liabilities 5 25
Currency/Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 1,588 3,174
Total derivative liabilities 1,149 365
Equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 607 203
Total derivative liabilities 735 489
Commodity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 27 55
Total derivative liabilities 3 7
Level 1 | Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 25 55
Total derivative liabilities 1 1
Level 1 | Currency    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 1 | Credit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 1 | Currency/Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 1 | Equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 2 0
Total derivative liabilities 2 6
Level 1 | Commodity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 10,768 13,022
Total derivative liabilities 5,949 6,281
Level 2 | Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 8,399 9,269
Total derivative liabilities 3,800 4,515
Level 2 | Currency    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 165 375
Total derivative liabilities 262 893
Level 2 | Credit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 21 1
Total derivative liabilities 5 25
Level 2 | Currency/Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 1,588 3,174
Total derivative liabilities 1,149 365
Level 2 | Equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 595 203
Total derivative liabilities 733 483
Level 2 | Commodity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 10 6
Total derivative liabilities 3 2
Level 3 | Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 6
Total derivative liabilities 3 2
Level 3 | Currency    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 3 | Credit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 3 | Currency/Interest Rate    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities 0 0
Level 3 | Equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 10 0
Total derivative liabilities 0 0
Level 3 | Commodity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total derivative assets 0 0
Total derivative liabilities $ 0 $ 0