Commitments (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Other Commitments [Line Items]  
Letters of Credit Outstanding, Amount $ 73.9
Revolving Credit Facility [Member]  
Other Commitments [Line Items]  
Letters of Credit Outstanding, Amount 41.5
Cash and Cash Equivalents [Member]  
Other Commitments [Line Items]  
Pledged Assets, Not Separately Reported, Other 3.8
Guarantee Type, Other [Member]  
Other Commitments [Line Items]  
Guarantor Obligations, Maximum Exposure, Undiscounted 14.4
Performance Guarantee [Member]  
Other Commitments [Line Items]  
Guarantor Obligations, Maximum Exposure, Undiscounted 24.0
Indemnification Agreement [Member]  
Other Commitments [Line Items]  
Guarantor Obligations, Maximum Exposure, Undiscounted $ 390.0