Finance Lease Receivables - Components of Finance Lease Receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finance lease receivables sold	$ 0.0	$ 7.4	$ 10.6
Allowance for credit losses	(4.4)	(4.4)	(4.6)
Finance Leases Portfolio Segment [Member]
Gross minimum lease receivable	26.6	63.3
Allowance for credit losses	(0.3)	(0.3)	$ (0.5)
Estimated unguaranteed residual values	1.1	3.7
Total Minimum Payments to be Received And Unguaranteed Residual Values	27.4	66.7
Unearned interest income	(1.0)	(2.9)
Unearned residuals	(0.1)	(0.1)
Unearned Interest Income and Residuals	(1.1)	(3.0)
Total	$ 26.3	$ 63.7