Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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

+ Details

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

- Definition

Amount of receivable related to a loss contingency accrual. For example, an insurance recovery receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12053-110248

+ Details

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

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=int_TaxAuthorityAssessmentMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=int_TaxAuthorityAdditionalAssessmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_CollectibilityOfReceivablesMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_MajorCustomersAxis=int_HanjinShippingCo.Ltd.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details) $ in Millions, ₩ in Billions	Jun. 30, 2017 USD ($)	Jun. 30, 2017 KRW (₩)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 KRW (₩)
Assessment
Loss Contingencies [Line Items]
Estimate of possible loss			$ 10.6	₩ 11.9
Additional Assessment
Loss Contingencies [Line Items]
Estimate of possible loss	$ 17.9	₩ 20.1
Collectibility of receivables \| Hanjin
Loss Contingencies [Line Items]
Loss contingency, outstanding receivable	$ 0.0