Commitments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Other Commitments [Line Items]
Letters of Credit Outstanding, Amount	$ 95.4
Revolving Credit Facility [Member]
Other Commitments [Line Items]
Letters of Credit Outstanding, Amount	47.9
Cash and Cash Equivalents [Member]
Other Commitments [Line Items]
Pledged Assets, Not Separately Reported, Other	5.2
Guarantee Type, Other [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	16.3
Performance Guarantee [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	27.6
Indemnification Agreement [Member]
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 440.0