Investments Finance Lease Receivables - Components of Finance Lease Receivables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance lease receivables sold	$ 11.1	$ 0.0	$ 7.4
Finance Leases Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross minimum lease receivable	39.0	26.6
Allowance for credit losses	0.4	0.3
Capital Leases, Net Investment in Sales Type Leases, Unguaranteed Residual Values of Leased Property	0.4	1.1
Capital Leases, Net Investment in Sales Type Leases, Minimum Payments to be Received And Unguaranteed Residual Values	39.0	27.4
Unearned interest income	3.0	1.0
Unearned residuals	0.1	0.1
Capital Leases, Net Investment in Sales Type Leases, Unearned Interest Income and Residuals	(3.1)	(1.1)
Capital Leases, Net Investment in Sales Type Leases, Receivable, Net	$ (35.9)	$ 26.3