Derivative Instruments and Hedging Activities (Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location) (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	$ 1,645	$ 1,485
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	26	0
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	2
Hedged asset, last-of-layer, amount	100	28
Hedge basis adjustment, last-of-layer	0	0
Hedged Asset, Discontinued Fair Value Hedge, Last-of-Layer, Amount	100
Finance receivables and Loans, net [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Asset, Fair Value Hedge	37,533	40,850
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	176	24
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	50
Hedged asset, last-of-layer, amount	10,200	21,400
Hedge basis adjustment, last-of-layer	126	19
Hedged Asset, Discontinued Fair Value Hedge, Last-of-Layer, Amount	12,800
Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Fair Value Hedge	12,879	13,001
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	120	67
Discontinued hedge | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	26	(5)
Discontinued hedge | Finance receivables and Loans, net [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged asset, discontinued fair value hedge, cumulative increase (decrease)	51	5
Discontinued hedge | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	$ 127	$ 67