Change in Financial Statement due to adoption of Policy (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Item Effected [Line Items]
Long-term debt	$ 3,420.4	$ 3,380.6
Other assets	158.2	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	19.1	(20.4)
Other assets	19.1	$ (20.4)
Previous Accounting Guidance [Member]
Item Effected [Line Items]
Long-term debt	3,439.5
Other assets	$ 177.3