Regulatory Capital and Other Regulatory Matters (Depository Institutions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets	$ 182,114	$ 182,165	$ 180,644
Dividends from bank subsidiary	3,500	1,200
BHC enhanced prudential standards, minimum	100,000
Statutory accounting practices, statutory amount available for dividend payments	111
Ally Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total assets	$ 172,800	$ 172,000