Commitments and Contingencies (Reserve for Unfunded Commitments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Feb. 23, 2024	Feb. 22, 2024	Dec. 31, 2023	Nov. 29, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Proposed annual rate					0.0336%
Estimated Special Assessment Charge	$ 11,900			$ 47,200
Special Assessment, Estimated Loss Attributable To Protection Of Uninsured Depositors		$ 20,400,000	$ 16,300,000
Special Assessment, Increase From Estimated Loss Attributable To Protection Of Uninsured Depositors		$ 4,100,000
SEC Schedule, 12-09, Allowance, Credit Loss
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 24,500			$ 24,700