Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details)

v3.19.2
DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2019
Jun. 30, 2019
Dec. 31, 2018
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity 2 years 7 months    
Document Period End Date   Jun. 30, 2019  
Notional Disclosures [Abstract]      
Derivative, Notional Amount $ 20,877 $ 20,877 $ 4,877
Fair Value Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 6,740 6,740 4,865
Cash Flow Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 11,937 11,937 12
Economic Hedging [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 2,200 2,200  
Loans Payable [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 11,925 11,925  
Loans Payable [Member] | Fair Value Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Loans Payable [Member] | Cash Flow Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 11,925 11,925  
Loans Payable [Member] | Economic Hedging [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Securities Investment [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 12 12 12
Securities Investment [Member] | Fair Value Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0 0
Securities Investment [Member] | Cash Flow Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 12 12 12
Securities Investment [Member] | Economic Hedging [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Other long-term debt      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 6,740 6,740 4,865
Other long-term debt | Fair Value Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 6,740 6,740 4,865
Other long-term debt | Cash Flow Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0 $ 0
Other long-term debt | Economic Hedging [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Unassigned [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 2,200 2,200  
Unassigned [Member] | Fair Value Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Unassigned [Member] | Cash Flow Hedging      
Notional Disclosures [Abstract]      
Derivative, Notional Amount 0 0  
Unassigned [Member] | Economic Hedging [Member]      
Notional Disclosures [Abstract]      
Derivative, Notional Amount $ 2,200 $ 2,200  
Asset conversion swaps Receive Fixed Generic      
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity 3 years 6 months 3 years 6 months 1 year 2 months 12 days
Notional Disclosures [Abstract]      
Derivative, Notional Amount $ 5,937 $ 5,937 $ 12
Liability conversion swaps Receive Fixed Generic      
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity   2 years 7 months 6 days 2 years 7 months 6 days
Notional Disclosures [Abstract]      
Derivative, Notional Amount 6,740 $ 6,740 $ 4,865
Interest Rate Floor [Member]      
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity   1 year 8 months 12 days  
Notional Disclosures [Abstract]      
Derivative, Notional Amount 8,200 $ 8,200  
Interest Rate Floor [Member] | Assigned [Member]      
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity   1 year 10 months 24 days  
Notional Disclosures [Abstract]      
Derivative, Notional Amount 6,000 $ 6,000  
Interest Rate Floor [Member] | Unassigned [Member]      
Credit Derivatives [Line Items]      
Derivative, Average Remaining Maturity   1 year 4 months 24 days  
Notional Disclosures [Abstract]      
Derivative, Notional Amount $ 2,200 $ 2,200