Change in Financial Statement due to adoption of Policy (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Item Effected [Line Items]
Long-term debt	$ 3,063.0	$ 3,380.6
Other assets	112.2	140.4
As Previously Reported [Member]
Item Effected [Line Items]
Long-term debt		3,401.0
Other assets		160.8
Reclassification [Member]
Item Effected [Line Items]
Long-term debt	17.7	(20.4)
Other assets	17.7	$ (20.4)
Previous Accounting Guidance [Member]
Item Effected [Line Items]
Long-term debt	3,080.7
Other assets	$ 129.9