Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 261	$ 261
Accumulated Amortization	114	52
Net Carrying Amount	147	209
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	218	218
Accumulated Amortization	90	41
Net Carrying Amount	128	177
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	43	43
Accumulated Amortization	24	11
Net Carrying Amount	$ 19	$ 32