Derivative Instruments and Hedging Activities (Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Closed Portfolio and Beneficial Interest, Last-of-Layer, Amortized Cost	$ 594	$ 230
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	1,266	1,217
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	46	18
Hedged asset, last-of-layer, amount	490	0
Hedge basis adjustment, last-of-layer	1
Finance receivables and Loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	32,274	33,312
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	277	135
Hedged asset, last-of-layer, amount	10,200	10,200
Hedge basis adjustment, last-of-layer	210	91
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Fair Value Hedge	8,877	11,995
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	202	24
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	30	18
Hedged asset, last-of-layer, amount	690	200
Hedge basis adjustment, last-of-layer	21	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)	67	44
Hedged asset, last-of-layer, amount	17,500	12,800
Hedge basis adjustment, last-of-layer	67	43
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease)	$ 200	$ 127