Other Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Goodwill [Line Items]
Proportional amortization investments	$ 1,997		$ 1,997		$ 1,866
Unfunded commitments for proportional amortization investments	1,025		$ 1,025		973
Unfunded commitments, period to be paid			5 years
Gain (loss) on nonmarketable equity investments, net	$ (11)	$ 0	$ (9)	$ (11)
Goodwill impairment					149
Goodwill, transfers					4
Corporate and Other
Goodwill [Line Items]
Goodwill impairment					149
Goodwill, transfers					4
Corporate and Other | Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations | Ally Lending
Goodwill [Line Items]
Goodwill impairment					$ 149