Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2024	Nov. 30, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Intangible Assets Goodwill And Other Assets [Line Items]
Goodwill	$ 1,100,000,000		$ 1,100,000,000	$ 1,100,000,000
Other intangible assets	27,255,000		27,255,000	35,506,000
Amortization of core deposit and customer list intangible assets			$ 8,300,000	$ 9,100,000	$ 10,300,000
Goodwill, impairment loss	$ 0	$ 0
Minimum [Member]
Intangible Assets Goodwill And Other Assets [Line Items]
Intangible asset, useful life	10 years		10 years
Maximum [Member]
Intangible Assets Goodwill And Other Assets [Line Items]
Intangible asset, useful life	16 years		16 years