Loans Held for Investment - Schedule of Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Losses
Recoveries Collected	$ 10.2	$ 12.4	$ 14.9
Provision for Loan, Lease, and Other Losses	67.8	32.2	82.7
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	204.1	227.7	220.1	$ 122.3
Financing Receivable, Allowance for Credit Loss, Writeoff	114.7	35.9	45.0
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	80.9	31.1	68.4
Non Owner Occupied Loans
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.4
Provision for Loan, Lease, and Other Losses			(4.2)
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			27.2	17.3
Financing Receivable, Allowance for Credit Loss, Writeoff			3.5
Commercial Real Estate Owner Occupied
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			1.9
Provision for Loan, Lease, and Other Losses			(2.7)
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			19.5	13.3
Financing Receivable, Allowance for Credit Loss, Writeoff			2.5
Commercial Real Estate Multifamily
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.7
Provision for Loan, Lease, and Other Losses			8.7
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			27.9	13.3
Financing Receivable, Allowance for Credit Loss, Writeoff			5.7
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			3.0
Provision for Loan, Lease, and Other Losses			1.8
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			74.6	43.9
Financing Receivable, Allowance for Credit Loss, Writeoff	25.4	7.6	11.7
Land Acquisition And Development Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.4
Provision for Loan, Lease, and Other Losses			(0.4)
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			1.3	0.5
Financing Receivable, Allowance for Credit Loss, Writeoff			2.6
Residential Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.1
Provision for Loan, Lease, and Other Losses			1.1
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			3.6	2.4
Financing Receivable, Allowance for Credit Loss, Writeoff			0.0
Commercial Real Estate Construction [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.0
Provision for Loan, Lease, and Other Losses			31.6
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			31.2	6.0
Financing Receivable, Allowance for Credit Loss, Writeoff			6.6
Construction Loans
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.5
Provision for Loan, Lease, and Other Losses			32.3
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			36.1	8.9
Financing Receivable, Allowance for Credit Loss, Writeoff			9.2
Residential Real Estate 1-4 Family
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.3
Provision for Loan, Lease, and Other Losses			6.9
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			20.5	13.4
Financing Receivable, Allowance for Credit Loss, Writeoff			0.2
Residential Real Estate
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.8
Provision for Loan, Lease, and Other Losses			6.9
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			22.1	14.6
Financing Receivable, Allowance for Credit Loss, Writeoff	1.0	0.6	0.3
Agricultural Real Estate Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.4
Provision for Loan, Lease, and Other Losses			1.5
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			5.9	1.9
Financing Receivable, Allowance for Credit Loss, Writeoff	0.0	0.0	0.2
Real Estate Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected	1.2	4.7	4.7
Provision for Loan, Lease, and Other Losses	17.7	35.2	42.5
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	139.4	160.1	138.7	69.3
Financing Receivable, Allowance for Credit Loss, Writeoff	39.6	18.5	21.4
Indirect consumer
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			2.3
Provision for Loan, Lease, and Other Losses			2.7
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			15.3	14.3
Financing Receivable, Allowance for Credit Loss, Writeoff	8.5	7.3	4.0
Other consumer
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			2.1
Provision for Loan, Lease, and Other Losses			2.2
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			5.2	4.6
Financing Receivable, Allowance for Credit Loss, Writeoff	3.9	4.1	3.7
Credit card consumer
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.6
Provision for Loan, Lease, and Other Losses			2.4
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			2.8	2.2
Financing Receivable, Allowance for Credit Loss, Writeoff	3.0	2.6	2.4
Total consumer loans
Financing Receivable, Allowance for Credit Losses
Recoveries Collected	4.9	4.7	5.0
Provision for Loan, Lease, and Other Losses	14.3	(1.0)	7.3
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	16.8	13.0	23.3	21.1
Financing Receivable, Allowance for Credit Loss, Writeoff	15.4	14.0	10.1
Commercial and Floor Plans
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			2.2
Provision for Loan, Lease, and Other Losses			15.1
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			49.0	27.1
Financing Receivable, Allowance for Credit Loss, Writeoff			6.6
Commercial Purpose Secured by 1-4 Family
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.1
Provision for Loan, Lease, and Other Losses			1.2
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			5.7	4.4
Financing Receivable, Allowance for Credit Loss, Writeoff			0.2
Commercial Borrower
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.0
Provision for Loan, Lease, and Other Losses			1.4
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			0.2	0.1
Financing Receivable, Allowance for Credit Loss, Writeoff			1.3
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected	3.8	2.6	2.3
Provision for Loan, Lease, and Other Losses	44.3	(3.9)	17.7
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	38.9	50.2	54.9	31.6
Financing Receivable, Allowance for Credit Loss, Writeoff	59.4	3.4	8.1
Agricultural Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses
Recoveries Collected	0.3	0.4	2.9
Provision for Loan, Lease, and Other Losses	4.6	0.8	0.9
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	9.0	4.4	3.2	0.3
Financing Receivable, Allowance for Credit Loss, Writeoff	$ 0.3	$ 0.0	5.4
Home Equity Loan
Financing Receivable, Allowance for Credit Losses
Recoveries Collected			0.5
Provision for Loan, Lease, and Other Losses			0.0
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest			1.6	$ 1.2
Financing Receivable, Allowance for Credit Loss, Writeoff			$ 0.1