Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Nov. 30, 2023
Lessee, Lease, Description [Line Items]
Impairment charges				$ 63
Operating lease ROU assets		$ 495	$ 139
Operating lease liabilities		488	$ 217
Operating leases, not yet commenced		$ 0
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		Other assets, net of allowance for credit losses of nil at both December 31, 2023 and 2022 (includes $10 million and $325 million designated under fair value option at December 31, 2023 and 2022, respectively)	Other assets, net of allowance for credit losses of nil at both December 31, 2023 and 2022 (includes $10 million and $325 million designated under fair value option at December 31, 2023 and 2022, respectively)
66 Hudson Boulevard Lease
Lessee, Lease, Description [Line Items]
Lease term					20 years
Operating lease ROU assets					$ 381
Operating lease liabilities					$ 324
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]					Other assets, net of allowance for credit losses of nil at both December 31, 2023 and 2022 (includes $10 million and $325 million designated under fair value option at December 31, 2023 and 2022, respectively)
Lease Termination and Associated Costs
Lessee, Lease, Description [Line Items]
Impairment charges		$ 22
Occupancy Expense, Net | Lease Termination and Associated Costs | 2020 - 2021 Restructuring Plan
Lessee, Lease, Description [Line Items]
Impairment charges	$ 29		$ 10	$ 40