Loans Held for Investment - Schedule of Contractual Aging of Loans by Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	$ 0.5		$ 0.5
Less loans charged-off	29.1	$ 6.2	56.4	$ 29.2
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11.9		11.9		$ 18.8
Nonaccrual loans	45.2		45.2		28.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	9,219.3		9,219.3		8,869.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,067.0		1,067.0		1,337.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,386.3		1,386.3		2,085.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2,007.2		2,007.2		1,675.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,499.3		1,499.3		1,215.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,147.4		1,147.4		774.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	2,007.2		2,007.2		1,706.1
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		47.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Total	9,219.3		9,219.3		8,869.2
Less loans charged-off			21.6		7.6
Commercial real estate | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,026.8		1,026.8		1,268.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,366.2		1,366.2		2,065.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,981.5		1,981.5		1,612.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,441.7		1,441.7		1,200.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,137.3		1,137.3		716.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,922.5		1,922.5		1,660.5
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		46.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Total	8,980.9		8,980.9		8,596.9
Commercial real estate | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.6		12.6		4.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	9.4		9.4		9.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21.1		21.1		42.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	18.3		18.3		12.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	2.2		2.2		27.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	36.9		36.9		17.1
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	100.5		100.5		113.7
Commercial real estate | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	27.6		27.6		65.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	10.7		10.7		11.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	4.6		4.6		18.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39.3		39.3		2.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.9		7.9		30.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	47.8		47.8		28.5
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	137.9		137.9		157.3
Commercial real estate | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0.0
Total					1.3
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3.7		3.7		3.5
Nonaccrual loans	0.1		0.1		17.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,307.9		1,307.9		1,826.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	261.2		261.2		501.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		758.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	490.8		490.8		356.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114.0		114.0		36.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.6		24.6		36.8
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		14.6
Total	1,307.9		1,307.9		1,826.5
Less loans charged-off			13.2		10.3
Total construction loans | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	256.1		256.1		493.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		735.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	484.4		484.4		331.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114.0		114.0		36.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.2		24.2		36.2
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		13.7
Total	1,296.0		1,296.0		1,768.0
Total construction loans | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3.2		3.2		0.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0		6.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6.4		6.4		1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.9
Total	9.6		9.6		9.5
Total construction loans | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.9		1.9		7.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0		4.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0		24.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.4		0.4		0.4
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	2.3		2.3		36.0
Total construction loans | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					13.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0.0
Total					13.0
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	4.9		4.9		15.6
Nonaccrual loans	14.3		14.3		10.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,217.8		2,217.8		2,244.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	15.6		15.6		45.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	71.3		71.3		359.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.5		423.5		522.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	491.3		491.3		501.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	456.3		456.3		89.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	270.0		270.0		222.2
Financing Receivable, Excluding Accrued Interest, Revolving	480.2		480.2		471.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.6		9.6		32.1
Total	2,217.8		2,217.8		2,244.3
Less loans charged-off			0.7		0.6
Residential | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	14.6		14.6		44.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	70.5		70.5		356.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	419.9		419.9		521.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	489.5		489.5		500.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	454.7		454.7		88.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	264.6		264.6		217.1
Financing Receivable, Excluding Accrued Interest, Revolving	480.2		480.2		471.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.3		9.3		32.1
Total	2,203.3		2,203.3		2,233.0
Residential | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.0		1.0		1.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.8		0.8		2.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	3.6		3.6		1.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.8		1.8		1.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.6		1.6		0.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.4		5.4		5.1
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.3		0.3		0.0
Total	14.5		14.5		11.3
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
Nonaccrual loans	4.7		4.7		5.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	726.4		726.4		716.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	105.5		105.5		96.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	76.0		76.0		154.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	138.7		138.7		133.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	130.2		130.2		98.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	88.9		88.9		58.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	161.3		161.3		136.7
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		32.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		7.0
Total	726.4		726.4		716.8
Less loans charged-off			0.0		0.0
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	92.2		92.2		86.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	65.0		65.0		123.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	113.6		113.6		126.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	121.4		121.4		93.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	79.9		79.9		56.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	159.4		159.4		124.3
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		31.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		7.0
Total	657.3		657.3		649.4
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.1		1.1		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.6		6.6		9.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.9		5.9		3.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.1		5.1		1.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.6		7.6		1.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1.0		1.0		11.3
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	27.3		27.3		30.8
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.2		12.2		8.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.4		4.4		20.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	19.2		19.2		3.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	3.7		3.7		2.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.4		1.4		0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.9		0.9		1.1
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	41.8		41.8		36.6
Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	22.9		22.9		39.7
Nonaccrual loans	64.3		64.3		61.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,471.4		13,471.4		13,656.8
Less loans charged-off	22.2	1.8	35.5	16.6
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		10.6
Nonaccrual loans	3.4		3.4		2.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	742.2		742.2		740.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	203.3		203.3		195.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	147.7		147.7		265.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	195.8		195.8		116.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	83.5		83.5		81.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	55.8		55.8		33.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	56.1		56.1		49.4
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	742.2		742.2		740.9
Less loans charged-off			6.9		7.3
Indirect consumer | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	203.0		203.0		194.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	146.9		146.9		264.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	194.8		194.8		115.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	83.0		83.0		81.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	55.4		55.4		32.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	55.6		55.6		48.8
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	738.7		738.7		737.8
Indirect consumer | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.3		0.3		0.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.8		0.8		0.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.0		1.0		0.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.5		0.5		0.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.4		0.4		0.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.5		0.5		0.6
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	3.5		3.5		3.1
Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.4		1.4		1.1
Nonaccrual loans	0.4		0.4		0.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	136.9		136.9		141.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	37.2		37.2		44.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	29.9		29.9		33.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	22.3		22.3		18.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	12.0		12.0		9.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	5.5		5.5		3.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	6.0		6.0		6.0
Financing Receivable, Excluding Accrued Interest, Revolving	24.0		24.0		26.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.2
Total	136.9		136.9		141.6
Less loans charged-off			2.9		4.1
Direct and advance lines | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	37.1		37.1		44.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	29.8		29.8		32.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	22.2		22.2		18.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	12.0		12.0		9.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	5.5		5.5		3.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.9		5.9		6.0
Financing Receivable, Excluding Accrued Interest, Revolving	24.0		24.0		26.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.2
Total	136.5		136.5		141.3
Direct and advance lines | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.1		0.1		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	0.4		0.4		0.3
Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.9		1.9		1.8
Nonaccrual loans	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	76.4		76.4		76.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	76.4		76.4		76.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	76.4		76.4		76.5
Less loans charged-off			2.1		2.6
Credit card | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	75.7		75.7		75.9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	75.7		75.7		75.9
Credit card | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.7		0.7		0.6
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	0.7		0.7		0.6
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11.4		11.4		13.5
Nonaccrual loans	3.8		3.8		3.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	955.5		955.5		959.0
Less loans charged-off	4.1	3.7	11.9	10.4
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		15.9
Nonaccrual loans	81.6		81.6		11.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,919.7		2,919.7		2,906.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	419.1		419.1		508.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	408.3		408.3		533.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.8		423.8		407.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	342.5		342.5		225.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	185.2		185.2		111.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	282.9		282.9		277.9
Financing Receivable, Excluding Accrued Interest, Revolving	851.2		851.2		836.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		8.2
Total	2,919.7		2,919.7		2,906.8
Less loans charged-off	2.5	0.7	8.7	2.2	3.4
Commercial | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	386.0		386.0		481.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	395.5		395.5		507.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	406.9		406.9		389.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	335.8		335.8		215.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	176.1		176.1		108.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	278.3		278.3		272.9
Financing Receivable, Excluding Accrued Interest, Revolving	783.5		783.5		762.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		7.6
Total	2,768.8		2,768.8		2,745.7
Commercial | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3.0		3.0		7.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.9		6.9		4.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	8.8		8.8		6.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.5		1.5		3.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.0		1.0		0.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1.0		1.0		1.9
Financing Receivable, Excluding Accrued Interest, Revolving	17.5		17.5		14.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.2
Total	39.7		39.7		39.5
Commercial | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	28.9		28.9		15.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.2		4.2		19.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.6		5.6		9.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.2		5.2		7.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	8.1		8.1		1.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	3.6		3.6		3.0
Financing Receivable, Excluding Accrued Interest, Revolving	7.1		7.1		58.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.4
Total	62.7		62.7		115.2
Commercial | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.2		1.2		3.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.7		1.7		1.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2.5		2.5		1.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	43.1		43.1		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	48.5		48.5		6.4
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		3.1
Nonaccrual loans	23.0		23.0		30.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	689.8		689.8		769.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	133.7		133.7		152.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	80.7		80.7		58.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.9		43.9		34.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.7		20.7		23.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	18.3		18.3		35.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.6		7.6		9.5
Financing Receivable, Excluding Accrued Interest, Revolving	384.8		384.8		449.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		6.5
Total	689.8		689.8		769.4
Less loans charged-off	0.3	$ 0.0	0.3	$ 0.0	0.0
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	81.3		81.3		105.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	52.5		52.5		57.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.2		43.2		31.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.5		20.5		22.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16.7		16.7		6.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.4		7.4		7.2
Financing Receivable, Excluding Accrued Interest, Revolving	355.7		355.7		421.9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		3.4
Total	577.3		577.3		656.0
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.5		0.5		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	3.6		3.6		0.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.7		0.7		0.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.0		1.0		0.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.2		0.2		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	5.2		5.2		9.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		3.1
Total	11.4		11.4		16.4
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	51.9		51.9		43.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	24.6		24.6		0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0		2.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.6		0.6		28.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		2.2
Financing Receivable, Excluding Accrued Interest, Revolving	23.9		23.9		18.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0		0.0
Total	101.1		101.1		97.0
Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Nonaccrual loans	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2.5		2.5		0.1
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	42.5		42.5		72.2
Nonaccrual loans	172.7		172.7		106.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	18,038.9		18,038.9		18,292.1
30 to 59 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	5.1		5.1		12.7
30 to 59 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3.6		3.6		3.1
30 to 59 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.6		2.6		11.9
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
30 to 59 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13.7		13.7		29.5
30 to 59 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		8.0
30 to 59 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.0		1.0		0.9
30 to 59 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.7
30 to 59 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		9.6
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	4.3		4.3		14.5
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		0.1
30 to 59 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
30 to 59 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	27.7		27.7		53.7
60 to 89 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.8		6.8		6.1
60 to 89 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
60 to 89 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.1		2.1		3.1
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
60 to 89 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9.0		9.0		9.6
60 to 89 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		2.2
60 to 89 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.4		0.4		0.2
60 to 89 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.5		0.5		0.5
60 to 89 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		2.9
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.5		1.5		1.1
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
60 to 89 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
60 to 89 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13.0		13.0		13.6
Equal to or Greater than 90 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Equal to or Greater than 90 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Equal to or Greater than 90 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Equal to or Greater than 90 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Equal to or Greater than 90 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
Equal to or Greater than 90 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Equal to or Greater than 90 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.6
Equal to or Greater than 90 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.8		0.8		1.0
Equal to or Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.6		0.6		0.3
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		3.0
Equal to or Greater than 90 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.0		0.0		0.0
Equal to or Greater than 90 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		4.9
Financial Asset, Not Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9,162.2		9,162.2		8,822.2
Financial Asset, Not Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,304.1		1,304.1		1,805.8
Financial Asset, Not Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,198.6		2,198.6		2,218.0
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	719.3		719.3		709.6
Financial Asset, Not Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13,384.2		13,384.2		13,555.6
Financial Asset, Not Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	730.7		730.7		727.6
Financial Asset, Not Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	135.1		135.1		140.2
Financial Asset, Not Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	74.5		74.5		74.7
Financial Asset, Not Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	940.3		940.3		942.5
Financial Asset, Not Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,831.7		2,831.7		2,879.4
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	665.0		665.0		735.9
Financial Asset, Not Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		0.1
Financial Asset, Not Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	$ 17,823.7		17,823.7		18,113.5
Year One, Originated, Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		1.7
Year One, Originated, Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year One, Originated, Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.3
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year One, Originated, Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.5
Year One, Originated, Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.2
Year One, Originated, Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year One, Originated, Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.4		0.2
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			5.7		0.3
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.7		3.2
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.5		0.5
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.9		0.4
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Three, Originated, Two Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		1.7
Year Three, Originated, Two Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			13.1		0.1
Year Three, Originated, Two Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Three, Originated, Two Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2.9		1.8
Year Three, Originated, Two Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.7		0.2
Year Three, Originated, Two Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Three, Originated, Two Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.0		0.5
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Four, Originated, Three Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			15.8		2.6
Year Four, Originated, Three Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Four, Originated, Three Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Four, Originated, Three Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.9		0.8
Year Four, Originated, Three Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.4
Year Four, Originated, Three Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Four, Originated, Three Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0.5
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0.0
Year Five, Originated, Four Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Five, Originated, Four Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.6
Year Five, Originated, Four Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.0
Year Five, Originated, Four Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Five, Originated, Four Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0.3
Year Five, Originated, Four Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Five, Originated, Four Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Year Five, Originated, Four Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.2
Year Five, Originated, Four Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Originated, More than Five Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		1.3
Originated, More than Five Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Originated, More than Five Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Originated, More than Five Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.9		0.7
Originated, More than Five Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.3		2.6
Originated, More than Five Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Originated, More than Five Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.1
Revolving | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2.1		2.6
Revolving | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.9		1.4
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		9.6
Revolving, Converted to Term | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.0		0.0
Revolving, Converted to Term | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			3.0		0.1
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			$ 0.0		$ 0.0