Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Variable Interest Entity [Line Items]
Carrying value of total assets	$ 192,877	$ 196,392	$ 196,165
Carrying value of total liabilities	179,220	182,626
Assets sold to nonconsolidated VIEs	3,620	2,639
Maximum exposure to loss in nonconsolidated VIEs	6,819	5,458
Non-recourse debt	17,011	17,570
Variable interest entity, deconsolidation of assets	1,100
Proceeds from sale of variable interest entity	1,100
Held-to-maturity securities	4,655	4,680
Other assets	9,348	9,395
Equity securities	788	810
On-balance sheet variable interest entities
Variable Interest Entity [Line Items]
Carrying value of total assets	6,189	7,075
Carrying value of total liabilities	1,318	1,513
Non-recourse debt	1,313	1,509
Other assets	445	461
On-balance sheet variable interest entities | Consumer | Automotive
Variable Interest Entity [Line Items]
Carrying value of total assets	15,132	16,415
Carrying value of total liabilities	1,418	1,614
Assets sold to nonconsolidated VIEs	0	0
Maximum exposure to loss in nonconsolidated VIEs	0	0
Assets held-in-trust	8,900	9,300
On-balance sheet variable interest entities | Consumer | Automotive | Nonrecourse
Variable Interest Entity [Line Items]
Non-recourse debt	100	100
Off-balance sheet variable interest entities
Variable Interest Entity [Line Items]
Carrying value of total assets	17,775	19,012
Carrying value of total liabilities	2,336	2,588
Off-balance sheet variable interest entities | Consumer | Automotive
Variable Interest Entity [Line Items]
Carrying value of total assets	133	81
Carrying value of total liabilities	0	0
Assets sold to nonconsolidated VIEs	3,509	2,514
Maximum exposure to loss in nonconsolidated VIEs	3,642	2,595
Held-to-maturity securities	127	78
Other assets	6	3
Off-balance sheet variable interest entities | Consumer | Other
Variable Interest Entity [Line Items]
Carrying value of total assets	0	0
Carrying value of total liabilities	0	0
Assets sold to nonconsolidated VIEs	111	125
Maximum exposure to loss in nonconsolidated VIEs	111	125
Off-balance sheet variable interest entities | Commercial | Other
Variable Interest Entity [Line Items]
Carrying value of total assets	2,510	2,516
Carrying value of total liabilities	918	974
Assets sold to nonconsolidated VIEs	0	0
Maximum exposure to loss in nonconsolidated VIEs	3,066	2,738
Equity securities	$ 46	$ 44