Fair Value Measurements Fair Value on a Nonrecurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Level 1
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	$ 0	$ 0
Level 2
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	1,558.4	1,367.5
Level 3
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	86.6	87.8
Fair Value, Total
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	$ 1,645.0	$ 1,455.3