Parent Company Condensed Financial Information (Condensed Statement of Cash Flows) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net Cash Provided by Operating Activities		$ 4,042	$ 3,739	$ 4,050
Investing activities
Proceeds from sales of finance receivables and loans initially held-for-investment		376	506	1,038
Originations and repayments of finance receivables and loans held-for-investment and other, net		2,896	15,353	4,252
Purchases of equity securities		(1,346)	(1,219)	(498)
Disposals of operating lease assets		3,438	2,681	2,625
Net change in nonmarketable equity investments		56	417	190
Other, net		(443)	(450)	(379)
Net cash (used in) provided by investing activities		(11,098)	8,427	(3,769)
Financing activities
Net change in short-term borrowings		(2,136)	(3,395)	(4,456)
Proceeds from issuance of long-term debt		2,997	3,660	6,915
Repayments of long-term debt		(6,068)	(16,107)	(17,224)
Repurchases of common stock		(1,994)	(106)	(1,039)
Preferred stock issuance		2,324	0	0
Trust preferred securities redemption		(2,710)	0	0
Common stock dividends paid		(324)	(289)	(273)
Preferred stock dividends paid		(57)	0	0
Net cash (used in) provided by financing activities		(3,848)	25	(1,530)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net (decrease) increase in cash and cash equivalents and restricted cash		(10,904)	12,194	(1,246)
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash at beginning of year		16,574	4,380	5,626
Cash and cash equivalents and restricted cash at end of year		5,670	16,574	4,380
Restricted Cash [Abstract]
Cash and cash equivalents		5,062	15,621
Restricted cash	[1]	608	953
Parent company
Operating activities
Net Cash Provided by Operating Activities		3,753	848	1,818
Investing activities
Proceeds from sales of finance receivables and loans initially held-for-investment		378	1,187	548
Originations and repayments of finance receivables and loans held-for-investment and other, net		189	601	(253)
Net change in loans — intercompany		(10)	(36)	718
Purchases of equity securities		(8)	0	0
Disposals of operating lease assets		0	1	3
Capital contributions to subsidiaries		0	(8)	(2)
Returns of contributed capital		24	23	259
Net change in nonmarketable equity investments		29	(7)	(13)
Other, net		44	(15)	(4)
Net cash (used in) provided by investing activities		646	1,746	1,256
Financing activities
Net change in short-term borrowings		(2,136)	(445)	104
Proceeds from issuance of long-term debt		765	2,885	801
Repayments of long-term debt		(777)	(2,444)	(2,173)
Net change in debt — intercompany		(336)	169	271
Repurchases of common stock		(1,994)	(106)	(1,039)
Preferred stock issuance		2,324	0	0
Trust preferred securities redemption		(2,710)	0	0
Common stock dividends paid		(324)	(290)	(273)
Preferred stock dividends paid		(57)	0	0
Net cash (used in) provided by financing activities		(5,245)	(231)	(2,309)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Net (decrease) increase in cash and cash equivalents and restricted cash		(846)	2,363	765
Cash and cash equivalents and restricted cash [Roll Forward]
Cash and cash equivalents and restricted cash at beginning of year		4,526	2,163	1,398
Cash and cash equivalents and restricted cash at end of year		3,680	4,526	$ 2,163
Restricted Cash [Abstract]
Cash and cash equivalents		3,647	4,482
Restricted cash		$ 33	$ 44

[1] Restricted cash balances relate primarily to Ally securitization arrangements. Refer to Note 13 for additional details describing the nature of restricted cash balances.