Commitments, Contingencies and Guarantees - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Jan. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures	$ 8,221,000	$ 5,088,000		$ 4,138,000	$ 5,088,000
Provision for off-balance sheet credit exposures	500,000	$ 0
Heartland Financial USA, Inc [Member]
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures			$ 3,600,000
Accrued Expenses and Taxes [Member]
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures	$ 8,200,000			$ 4,100,000