Derivative Instruments and Hedging Activities (Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	$ 1,259	$ 1,217
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	39	18
Closed Portfolio and Beneficial Interest, Last-of-Layer, Amortized Cost	592	230
Hedged asset, last-of-layer, amount	0	0
Finance receivables and Loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	28,393	33,312
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	225	135
Hedged asset, last-of-layer, amount	9,400	10,200
Hedge basis adjustment, last-of-layer	153	91
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Fair Value Hedge	8,656	11,995
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	169	24
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	28	18
Hedged asset, last-of-layer, amount	1,200	200
Hedge basis adjustment, last-of-layer	20	2
Discontinued hedge | Finance receivables and Loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	72	44
Hedged asset, last-of-layer, amount	18,500	12,800
Hedge basis adjustment, last-of-layer	72	43
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	$ 203	$ 127