Commitments and Contingent Liabilities (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Long-term Purchase Commitment [Line Items]
IRS proposed unfavorable tax adjustments	$ 85.0
Gross unrecognized tax benefits	101.0	$ 120.0
Tax impact of net unrecognized tax benefits, if reversed	39.0
Letters of credit issued	8.1
Revolving Credit Facility [Member]
Long-term Purchase Commitment [Line Items]
Letters of credit issued	$ 5.1

Estimated amount of loss resulting from an adverse tax position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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