Loans Receivable - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecast changes	$ 107.4	$ (206.5)	$ (206.5)
Certain Loans Acquired In Transfer Accounted For As Loans Accretable Yield Reclassifications From Nonaccretable Difference Forecast Changes, By Percentage	2.30%
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecast changes	$ 26.7		(75.9)
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecast changes	80.7		$ (130.6)
Forecast Changes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecast changes	(44.3)
COVID-19 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecast changes	$ (162.2)