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Derivatives and Hedging Activities - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2026 USD ($) Derivative	Sep. 30, 2025 USD ($)	Sep. 30, 2026 USD ($) Derivative	Sep. 30, 2025 USD ($)	Dec. 31, 2025 USD ($) Derivative
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Collateral posted with market value on liability positions with credit risk-related contingent features	$ 78,700,000		$ 78,700,000		$ 16,000,000
Interest Rate Swaps and Caps [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps \| Derivative	383		383		368
Aggregate notional amount	$ 2,800,000,000		$ 2,800,000,000		$ 2,600,000,000
Income (loss) on derivative instrument not designated hedges	$ 2,800,000	$ 3,200,000	$ 6,800,000	$ 6,600,000
Risk Participation in Agreements [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps \| Derivative	24		24		26
Aggregate notional amount	$ 331,500,000		$ 331,500,000		$ 271,800,000
Risk Participation out Agreement [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps \| Derivative	9		9		9
Aggregate notional amount	$ 88,800,000		$ 88,800,000		$ 89,500,000
Other Contract [Member] \| Forward TBA Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount	$ 46,500,000		$ 46,500,000		$ 91,000,000