Quarterly report pursuant to Section 13 or 15(d)

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortization Method (Details)

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LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortization Method (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]          
Fair value, end of period $ 248   $ 248   $ 238
Automobile          
Servicing Asset at Amortized Cost, Balance [Roll Forward]          
Carrying value, beginning of period 6 $ 15 8 $ 18  
Amortization and other (1) (3) (3) (6)  
Fair value, end of period 5 12 5 12  
Carrying value, end of period $ 5 $ 12 $ 5 $ 12  
Automobile | Amortization method          
Servicing Asset at Amortized Cost, Balance [Roll Forward]          
Weighted-average life (years) 3 years 2 months 3 years 9 months 3 years 2 months 3 years 9 months