Fair Value - Unfunded Loan and Lease Commitments and Letters of Credit (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Unfunded loan and lease commitments and letters of credit
Aggregate commitments to extend credit, standby letters of credit and commercial letters of credit	$ 6,100.0	$ 6,000.0
Significant Unobservable Inputs (Level 3)
Unfunded loan and lease commitments and letters of credit
Aggregate commitments to extend credit, standby letters of credit and commercial letters of credit	6,100.0	6,000.0
Estimated fair value of unfunded loan and lease commitments and letters of credit	$ 46.9	$ 47.4