Cost Of Revenue, Excluding Hedging Impact Of Hedges

No definition available.

Name:	int_CostOfRevenueExcludingHedgingImpactOfHedges
Namespace Prefix:	int_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Revenue, Excluding Impact Of Hedges

+ References

No definition available.

+ Details

Name:	int_RevenueExcludingImpactOfHedges
Namespace Prefix:	int_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624258-113959

+ Details

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

- Definition

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109977999&loc=d3e76258-113986

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

+ References

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624258-113959

+ Details

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

- Definition

The aggregate cost of goods produced and sold and services rendered during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

Name:	us-gaap_CostOfRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624258-113959

+ Details

Name:	us-gaap_DerivativeNetLiabilityPositionAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

+ References

+ Details

Name:	us-gaap_GainLossOnFairValueHedgeIneffectivenessNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of asset hedged in fair value hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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

- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959

+ Details

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

- Definition

Amount, after tax and before reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

Name:	us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109978405&loc=d3e80720-113993

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

+ Details

Name:	us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_SalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OtherIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_FairValueHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Instruments - Effect on Income (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (loss) on derivative
Carrying Amount of Hedged Asset/(Liabilities)	$ 44,700,000				$ 50,900,000				$ 44,700,000	$ 50,900,000
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Asset/(Liabilities)	(6,600,000)				2,700,000				(6,600,000)	2,700,000
Revenue	9,988,600,000	$ 10,429,500,000	$ 10,150,800,000	$ 9,181,300,000	8,872,000,000.0	$ 8,543,000,000.0	$ 8,086,200,000	$ 8,194,300,000	39,750,300,000	33,695,500,000	$ 27,015,800,000
Cost of revenue									38,731,800,000	32,763,300,000	26,116,800,000
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										(7,600,000)	38,800,000
Gains or (losses) recognized in income representing hedge ineffectiveness									0	0	0
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)									41,500,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)										(7,900,000)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)									20,900,000
Derivative, credit-risk related contingent features
Net derivative liability positions with credit contingent features	7,200,000				11,800,000				7,200,000	11,800,000
Maximum potential collateral requirements	7,200,000				11,800,000				7,200,000	11,800,000
Collateral posted	$ 0				$ 0				0	0
Revenue
Gain (loss) on derivative
Revenue									39,750,300,000	33,695,500,000	27,015,800,000
Total amount of income and expense line items excluding the impact of hedges, Revenue									39,773,700,000	33,736,800,000	26,997,700,000
Cost of revenue
Gain (loss) on derivative
Cost of revenue									38,731,800,000	32,763,300,000	26,116,800,000
Total amount of income and expense line items excluding the impact of hedges, Cost of revenue									38,776,100,000	32,774,200,000	26,123,100,000
Commodity contracts \| Revenue
Gain (loss) on derivative
Realized and Unrealized Gain (Loss) on Hedged Items									0
Realized and Unrealized Gain (Loss) on Derivative Instruments									0
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income									(23,500,000)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										(41,300,000)	18,100,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)									130,300,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)										(7,800,000)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)									(23,500,000)
Commodity contracts \| Cost of revenue
Gain (loss) on derivative
Realized and Unrealized Gain (Loss) on Hedged Items									(1,600,000)
Realized and Unrealized Gain (Loss) on Derivative Instruments									500,000
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income									45,500,000
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										33,700,000	20,800,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)									(87,800,000)
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)										(100,000)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)									45,500,000
Foreign currency contracts \| Other (expense) income, net
Gain (loss) on derivative
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										0	0
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)									(1,100,000)
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)										0	0
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)									(1,100,000)
Derivatives designated as hedging instruments \| Fair value hedges \| Commodity contracts \| Revenue
Gain (loss) on derivative
Realized and Unrealized Gain (Loss) on Hedged Items										0	0
Realized and Unrealized Gain (Loss) on Derivative Instruments										0	0
Derivatives designated as hedging instruments \| Fair value hedges \| Commodity contracts \| Cost of revenue
Gain (loss) on derivative
Realized and Unrealized Gain (Loss) on Hedged Items										13,000,000.0	10,800,000
Realized and Unrealized Gain (Loss) on Derivative Instruments										(35,700,000)	(25,300,000)
Derivatives designated as hedging instruments \| Cash flow hedges
Gain (loss) on derivative
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)											32,300,000
Derivatives designated as hedging instruments \| Cash flow hedges \| Commodity contracts \| Revenue
Gain (loss) on derivative
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										(41,300,000)	18,100,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)											(145,800,000)
Derivatives designated as hedging instruments \| Cash flow hedges \| Commodity contracts \| Cost of revenue
Gain (loss) on derivative
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Effective Portion)										33,700,000	20,800,000
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)											178,100,000
Derivatives not designated as hedging instruments
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									34,500,000	50,800,000	7,300,000
Derivatives not designated as hedging instruments \| Commodity contracts
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									27,800,000	61,800,000	(1,900,000)
Derivatives not designated as hedging instruments \| Commodity contracts \| Revenue
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									147,600,000	(500,000)	29,700,000
Derivatives not designated as hedging instruments \| Commodity contracts \| Cost of revenue
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									(119,800,000)	62,300,000	(31,600,000)
Derivatives not designated as hedging instruments \| Foreign currency contracts
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									6,700,000	(11,000,000.0)	9,200,000
Derivatives not designated as hedging instruments \| Foreign currency contracts \| Revenue
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									1,400,000	(3,200,000)	10,000,000.0
Derivatives not designated as hedging instruments \| Foreign currency contracts \| Other (expense) income, net
Gain (loss) on derivative
Amount of Realized and Unrealized Gain (Loss)									$ 5,300,000	$ (7,800,000)	$ (800,000)