Condensed Consolidated Balance Sheet & Mini Balance Sheet - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets [Abstract]
Cash and cash equivalents, noninterest-bearing	$ 747	$ 724
Cash and cash equivalents, interest-bearing	15,031	14,897
Total cash and cash equivalents	15,778	15,621
Equity securities	1,068	1,071
Available-for-sale securities	33,446	29,830
Held-to-maturity securities	1,197	1,253
Loans held-for-sale, net	630	406
Finance receivables and loans, net [Abstract]
Finance receivables and loans, net	113,076	118,534
Allowance for loan losses	3,152	3,283
Total finance receivables and loans, net	109,924	115,251
Investment in operating leases, net	9,944	9,639
Premiums receivable and other insurance assets	2,725	2,679
Other assets	7,167	6,415
Total assets	181,879	182,165
Liabilities and Equity [Abstract]
Deposit liabilities, noninterest-bearing	155	128
Deposit liabilities, interest-bearing	139,430	136,908
Total deposit liabilities	139,585	137,036
Short-term borrowings	0	2,136
Long-term debt	20,503	22,006
Interest payable	453	412
Unearned insurance premiums and service revenue	3,487	3,438
Accrued expenses and other liabilities	3,226	2,434
Total liabilities	$ 167,254	$ 167,462
Equity [Abstract]
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	1,100,000,000	1,100,000,000
Total common stock shares issued	503,643,221	501,237,055
Common stock, shares outstanding	371,804,633	374,674,415
Common Stocks, Including Additional Paid in Capital	$ 21,566	$ 21,544
Accumulated deficit	(3,555)	(4,278)
Accumulated other comprehensive income	$ 27	$ 631
Treasury stock, shares	131,838,588	126,562,640
Treasury stock, at cost	$ (3,413)	$ (3,194)
Total equity	14,625	14,703
Total liabilities and equity	181,879	182,165
Available-for-sale debt securities | Available-for-sale securities
Assets [Abstract]
Debt securities, available-for-sale, amortized cost	33,336	28,936
Available-for-sale securities	33,446	29,830
Held-to-maturity securities
Assets [Abstract]
Held-to-maturity securities, fair value	1,250	1,331
Held-to-maturity securities	1,197	1,253
Held-to-maturity securities | Held-to-maturity securities
Assets [Abstract]
Held-to-maturity securities, fair value	1,250	1,331
On-balance sheet variable interest entities
Finance receivables and loans, net [Abstract]
Allowance for loan losses	307	285
Total finance receivables and loans, net	12,155	13,213
Other assets	1,266	983
Total assets	13,421	14,196
Liabilities and Equity [Abstract]
Long-term debt	3,553	4,158
Accrued expenses and other liabilities	4	3
Total liabilities	3,557	4,161
On-balance sheet variable interest entities | Consumer portfolio segment
Finance receivables and loans, net [Abstract]
Finance receivables and loans, net	8,551	7,630
On-balance sheet variable interest entities | Commercial portfolio segment
Finance receivables and loans, net [Abstract]
Finance receivables and loans, net	$ 3,911	$ 5,868