Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 01, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 145.5	$ 146.1				$ 73.0	$ 75.0	$ 74.2		$ 73.0
Off-Balance Sheet, Credit Loss, Liability						0.0
Credit Extension Commitments	2,173.2					2,067.0
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	691.9					671.8
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	58.8					42.7
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Entity Information [Line Items]
Accounts Receivable, Allowance for Credit Loss			$ 2.3		$ 103.0	0.0			$ 0.0	0.0
Off-Balance Sheet, Credit Loss, Liability	1.2	3.5		$ 0.0	2.3	1.2	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Cumulative Effect, Period of Adoption, Adjustment
Entity Information [Line Items]
Accounts Receivable, Allowance for Credit Loss	30.0				30.0
Off-Balance Sheet, Credit Loss, Liability					$ 2.3
Agricultural
Entity Information [Line Items]
Accounts Receivable, Allowance for Credit Loss	0.9	$ 0.9				$ 1.6
Agricultural | Cumulative Effect, Period of Adoption, Adjustment
Entity Information [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ (0.6)