Fair Value Measurements, Fair Value of Non financial Assets and Liabilities (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Increase (decrease) in basic earnings per share resulting from adjustment			$ 0.00
Increase (decrease) in diluted earnings per share resulting from adjustment			$ 0.00
Asset Retirement Obligation, Roll Forward
Beginning balance	$ 4.8	$ 4.4	$ 4.1
Liabilities settled during the period	(0.2)	0.0	(0.2)
Accretion expense	0.3	0.4	0.4
Adjustment to accretion expense due to revisions to estimated cash flow and timing of expenditure	0.0	0.0	0.1
Ending balance	$ 4.9	$ 4.8	$ 4.4