Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details)

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FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
MSRs    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Mortgage banking income $ (1) $ 1
Securities gains (losses) 0 0
Other expense 0  
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings 1 1
Derivative Financial Instruments, Assets [Member]    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Mortgage banking income (6) (5)
Securities gains (losses) 0 0
Other expense 0  
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings (6) (5)
Municipal securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Mortgage banking income 0 0
Securities gains (losses) 0 (1)
Other expense (1)  
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings 1 1
Asset-backed securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Mortgage banking income 0 0
Securities gains (losses) (2) 0
Other expense 0  
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings 2 0
Automobile    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Mortgage banking income 0 0
Securities gains (losses) 0 0
Other expense 0  
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings $ 0 $ 0