Loans Held for Investment - Schedule of Troubled Debt Restructurings (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022 USD ($) note	Sep. 30, 2022 USD ($) note
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	3	12
Troubled debt restructurings	$ 48.1	$ 71.7
Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	3.2
Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	2.0	15.7
Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 46.1	$ 52.8
Commercial Real Estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	4
Troubled debt restructurings	$ 46.1	$ 53.7
Commercial Real Estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	3.2
Commercial Real Estate | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	4.2
Commercial Real Estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial Real Estate | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 46.1	$ 46.3
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note		2
Troubled debt restructurings		$ 0.6
Residential | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Residential | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.6
Residential | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Residential | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		$ 0.0
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	2
Troubled debt restructurings	$ 0.1	$ 9.0
Agricultural | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Agricultural | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.1	9.0
Agricultural | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Agricultural | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 0.0	$ 0.0
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	3
Troubled debt restructurings	$ 1.9	$ 2.5
Commercial | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	1.9	1.9
Commercial | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 0.0	$ 0.6
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note		1
Troubled debt restructurings		$ 5.9
Agricultural | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		$ 5.9