Name:	int_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix:	int_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the settlements that have taken place during the period in relation to assets and liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

No definition available.

+ Details

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

- Definition

Represents the change in unrealized gains (losses) using significant unobservable inputs (level 3), relating to instruments held as of the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

Represents assets and liabilities measured at fair value using significant unobservable inputs (level 3), which is required for the purpose of reconciliation of the beginning and ending balances.

+ References

No definition available.

+ Details

Name:	int_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetsAndLiabilitiesValue
Namespace Prefix:	int_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the amount of the total realized and unrealized gains or losses for the period which are included in the statement of income (or changes in net assets); the fair value of which assets and liabilities was or is measured on a recurring basis using significant unobservable inputs (Level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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

Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Change in fair value of assets and liabilities measured on recurring basis, utilized Level 3 inputs
Beginning of Period, (Liabilities) Assets				$ (4,922)
Realized and Unrealized Gains (Losses) Included in Earnings				(144)
Settlements				(90)
End of Period, Liabilities		(5,156)		(5,156)
Change in Unrealized Losses Relating to Instruments Still Held at end of Period				(144)
Commodity contracts, net
Change in fair value of assets and liabilities measured on recurring basis, utilized Level 3 inputs
Beginning of Period, (Liabilities) Assets				90
Settlements				(90)
Earn-out
Change in fair value of assets and liabilities measured on recurring basis, utilized Level 3 inputs
Beginning of Period, (Liabilities) Assets	(4,323)	(5,151)	(4,194)	(5,012)
Realized and Unrealized Gains (Losses) Included in Earnings	19	(5)	(110)	(144)
Settlements	4,304		4,304
End of Period, Liabilities		(5,156)		(5,156)
Change in Unrealized Losses Relating to Instruments Still Held at end of Period		$ (5)		$ (144)