Fair Value Measurements - Summary of Estimated Fair Values of Significant Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity investment securities, Fair Value	$ 7,404,724	$ 7,453,123
Carrying Amount | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	2,512,276	2,074,434
Held-to-maturity investment securities, Carrying Amount	8,297,927	8,444,191
Loans and leases, net	52,342,902	51,815,602
Securities sold under agreements to repurchase and federal funds purchased	83,395	344,168
FHLB advances	2,910,011	2,110,108
Long-term debt	907,410	909,185
Carrying Amount | Fair Value, Nonrecurring | Deposit liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits	58,052,837	56,518,126
Carrying Amount | Fair Value, Nonrecurring | Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits	7,522,392	8,234,954
Level 1 | Fair Value | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	2,512,276	2,074,434
Level 2 | Fair Value | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity investment securities, Fair Value	7,404,724	7,453,123
Securities sold under agreements to repurchase and federal funds purchased	83,385	344,166
FHLB advances	2,907,940	2,107,790
Long-term debt	906,286	860,200
Level 2 | Fair Value | Fair Value, Nonrecurring | Deposit liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits	58,052,837	56,518,126
Level 2 | Fair Value | Fair Value, Nonrecurring | Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits	7,495,259	8,211,582
Level 3 | Fair Value | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans and leases, net	$ 50,536,923	$ 50,245,305