Variable Interest Entities (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Type of Entity	one
Variable Interest, Held by Entity [Member]
Carrying amounts of assets and liabilities of the VIE
Operating assets, net of accumulated depreciation	$ 84.5	$ 88.1
Nonrecourse debt	$ 9.2	$ 15.9