Fair Value Measurements Fair Value on a Nonrecurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
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	1,377.4	2,292.4
Level 3
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	85.8	90.8
Fair Value, Total
Fair value assets and liabilities measured on recurring and nonrecurring basis
Total long-term debt	$ 1,463.2	$ 2,383.2