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, 2021	Dec. 31, 2020
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	$ 5,307	$ 1,259
Hedged asset, fair value hedge, cumulative increase (decrease)	(26)	39
Closed portfolio and beneficial interest, last-of-layer, amortized cost	3,900	592
Hedged asset, last-of-layer, amount	3,000
Hedge basis adjustment, last-of-layer	(30)
Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	45,463	28,393
Hedged asset, fair value hedge, cumulative increase (decrease)	78	225
Hedged asset, last-of-layer, amount	16,600	9,400
Hedge basis adjustment, last-of-layer	28	153
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge	7,083	8,656
Hedged liability, fair value hedge, cumulative increase (decrease)	108	169
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	4	28
Hedged asset, last-of-layer, amount	4,700	1,200
Hedge basis adjustment, last-of-layer	9	20
Discontinued hedge | Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	50	72
Hedged asset, last-of-layer, amount	20,100	18,500
Hedge basis adjustment, last-of-layer	50	72
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, discontinued fair value hedge, cumulative increase (decrease)	$ 132	$ 203