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Securities - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2024
Schedule of Available-for-sale Securities [Line Items]
Realized gains on sales	$ 22.0
Investments pledged, carrying value	194.1	$ 221.9
Investments pledged, carrying par value		30.0
Federal Reserve's Bank Term Funding Program [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments pledged, carrying value	$ 61.7	$ 29.9

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