Allowance for Credit Losses - Summary of Allowance for Credit Losses (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan, Lease, and Other Losses		$ (0.1)
Allowance for credit losses and recorded investment in financing receivables
Balance at January 1	$ 4.4	4.6
Write-offs	(0.1)	(0.1)
Balance at September 30	4.3	4.4
Finance Leases Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan, Lease, and Other Losses		(0.1)
Allowance for credit losses and recorded investment in financing receivables
Balance at January 1	0.3	0.5
Write-offs	(0.1)	(0.1)
Balance at September 30	0.2	0.3
Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan, Lease, and Other Losses		0.0
Allowance for credit losses and recorded investment in financing receivables
Balance at January 1	4.1	4.1
Write-offs	0.0	0.0
Balance at September 30	$ 4.1	$ 4.1