Derivative Instruments and Hedging Activities (Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	$ 5,380	$ 1,259
Hedged asset, fair value hedge, cumulative increase (decrease)	9	39
Closed portfolio and beneficial interest, last-of-layer, amortized cost	3,500	592
Hedged asset, last-of-layer, amount	2,900
Hedge basis adjustment, last-of-layer	(5)
Finance receivables and loans, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, fair value hedge	36,462	28,393
Hedged asset, fair value hedge, cumulative increase (decrease)	124	225
Hedged asset, last-of-layer, amount	12,700	9,400
Hedge basis adjustment, last-of-layer	63	153
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, fair value hedge	7,189	8,656
Hedged liability, fair value hedge, cumulative increase (decrease)	102	169
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	15	28
Hedged asset, last-of-layer, amount	1,700	1,200
Hedge basis adjustment, last-of-layer	15	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)	61	72
Hedged asset, last-of-layer, amount	20,100	18,500
Hedge basis adjustment, last-of-layer	61	72
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged liability, discontinued fair value hedge, cumulative increase (decrease)	$ 127	$ 203