Accounts Receivable, Net of Allowance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Change in Accounting Estimate [Line Items]
Provisions for doubtful accounts	$ 0.2	$ 0.3	$ 0.7	$ 0.8
Financing Receivable [Member]
Change in Accounting Estimate [Line Items]
Increase in cash collections from non-recourse financing arrangement	$ 28.0
Uncollectible Receivables [Member]
Change in Accounting Estimate [Line Items]
Change in estimate, provision for doubtful accounts		$ 0.5		$ 0.5