Nature of Business and Summary of Significant Accounting Policies - Accounts Receivable and Allowances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Receivables Sold and Derecognized	$ 2,654.2	$ 3,314.8
Proceeds Collected on Behalf of Financial Institutions	2,254.9	3,153.4
Net Proceeds Received From (Paid to) Financial Institutions	66.5	13.4
Deferred Purchase Price	0.7	66.9
Pledged Receivables at December 31	177.5	43.0
Receivables sold	238.0	119.0
Amount transferred subject to continuing involvement	$ 562.0	$ 559.0