Business Combinations - Net Assets Acquired (Details) - USD ($) $ in Millions			12 Months Ended
	Mar. 20, 2023	Dec. 01, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair value adjustments:
Bargain purchase gain on Signature Transaction, as initially reported		$ 159	$ 2,131	$ 159	$ 0
Signature Bridge Bank
Business Acquisition [Line Items]
Net assets acquired before fair value adjustments	$ 2,973
Fair value adjustments:
Loans	(727)
Core deposit and other intangibles	464
Certificates of deposit	27
Other net assets and liabilities	39
FDIC Equity Appreciation Instrument	(85)
Deferred tax liability	(690)
Measurement period adjustments, excluding taxes	28
Change in deferred tax liability	102
Signature Bridge Bank | Previously Reported
Business Acquisition [Line Items]
Net assets acquired before fair value adjustments	2,086
Fair value adjustments:
Bargain purchase gain on Signature Transaction, as initially reported	2,001
Signature Bridge Bank | Restatement Adjustment
Business Acquisition [Line Items]
Net assets acquired before fair value adjustments	2,216
Fair value adjustments:
Bargain purchase gain on Signature Transaction, as initially reported	$ 2,131