Fair Value Measurements Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Level 1
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	$ 0.0	$ 0.0
Level 2
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	1,571.5	1,531.4
Level 3
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	74.3	75.2
Fair Value, Total
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	$ 1,645.8	$ 1,606.6