Accounts Receivable, Net of Allowance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Accounts Receivable, Net of Allowance [Line Items]
Provisions for doubtful accounts	$ 0.4	$ 0.4	$ 1.1	$ 2.0
Interest Expense [Member] | Financing Receivable [Member]
Schedule of Accounts Receivable, Net of Allowance [Line Items]
Non-recourse financing arrangement, discount charge	$ 2.1	$ 0.8	$ 4.7	$ 1.7