Contingent Liabilities (Details) $ in Millions	Dec. 31, 2017 USD ($)
Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Loss contingency, range of possible loss, portion not accrued	$ 7.5
Surety Bonds [Member]
Line of Credit Facility [Line Items]
Loss contingency, range of possible loss, portion not accrued	2.3
Bank Guaranties [Member]
Line of Credit Facility [Line Items]
Loss contingency, range of possible loss, portion not accrued	$ 1.7

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant