Commitments and Contingencies (Outstanding Financial Instruments Contract Amounts Represent Credit Risk) (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 11,705,267	$ 12,563,441
Standby letter of credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	497,573	482,462
Commercial letter of credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	36,300	54,382
Commitments to extend credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 11,171,394	$ 12,026,597