Consolidated Balance Sheet & Mini Balance Sheet - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Cash and cash equivalents, noninterest-bearing	$ 810	$ 844
Cash and cash equivalents, interest-bearing	3,727	3,408
Total cash and cash equivalents	4,537	4,252
Equity securities	773	518
Available-for-sale securities	25,303	22,303
Held-to-maturity securities	2,362	1,899
Loans held-for-sale, net	314	108
Finance receivables and loans, net [Abstract]
Finance receivables and loans, net of unearned income	129,926	122,893
Allowance for loan losses	1,242	1,276
Total finance receivables and loans, net	128,684	121,617
Investment in operating leases, net	8,417	8,741
Premiums receivable and other insurance assets	2,326	2,047
Other assets	6,153	5,663
Total assets	178,869	167,148
Liabilities and Equity [Abstract]
Deposit liabilities, noninterest-bearing	142	108
Deposit liabilities, interest-bearing	106,036	93,148
Total deposit liabilities	106,178	93,256
Short-term borrowings	9,987	11,413
Long-term debt	44,193	44,226
Interest payable	523	375
Unearned insurance premiums and service revenue	3,044	2,604
Accrued expenses and other liabilities	1,676	1,780
Total liabilities	165,601	153,654
Equity [Abstract]
Common stock and paid-in capital	21,345	21,245
Accumulated deficit	(5,489)	(6,406)
Accumulated other comprehensive loss	(539)	(235)
Treasury stock, at cost	(2,049)	(1,110)
Total equity	13,268	13,494
Total liabilities and equity	178,869	167,148
Variable interest entity
Finance receivables and loans, net [Abstract]
Finance receivables and loans, net of unearned income	18,086	20,623
Allowance for loan losses	114	136
Total finance receivables and loans, net	17,972	20,487
Investment in operating leases, net	164	444
Other assets	767	689
Total assets	18,903	21,620
Liabilities and Equity [Abstract]
Long-term debt	10,482	10,197
Accrued expenses and other liabilities	12	9
Total liabilities	$ 10,494	$ 10,206