Commitments and Contingencies (Outstanding Financial Instruments Contract Amounts Represent Credit Risk) (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 10,781,492	$ 7,152,331
Standby letter of credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	379,495	224,061
Commercial letter of credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	68,544	58,175
Commitments to extend credit
Loss Contingencies [Line Items]
Unused commitments to extend credit	$ 10,333,453	$ 6,870,095