Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Standby letters of credit and surety bonds		$ 34.6
Outstanding commitments to fund new loan and lease transactions		$ 949.3
Funding commitments for loans and leases expiration period		90 days
Other commitments due in 2025		$ 207.1
Other commitments due in 2026		94.2
Other commitments due in 2027		95.1
Other commitments due in 2028		71.8
Other commitments due in 2029		66.5
Other commitments due in 2029 and beyond		90.6
Environmental activities expenditures		$ 4.4	$ 3.0	$ 4.6
Environmental Remediation Expense, Statement of Income or Comprehensive Income [Extensible Enumeration]		Costs and Expenses	Costs and Expenses	Costs and Expenses
Non-recurring settlement charge, pre-tax	$ 600.0
Non-recurring settlement charge, after-tax	$ 446.4