Other Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Gain (loss) on nonmarketable equity investments, net	$ (10)	$ (132)	$ 142
Goodwill impairment	149	$ 0	$ 0
Transfer to assets of operations held-for-sale	4
Corporate and Other
Goodwill [Line Items]
Goodwill impairment	149
Transfer to assets of operations held-for-sale	4
Corporate and Other | Disposal Group, Held-for-Sale, Not Discontinued Operations | Ally Lending
Goodwill [Line Items]
Goodwill impairment	$ 149