XML 50 R39.htm IDEA: XBRL DOCUMENT ﻿
v2.3.0.11

Derivative instruments (Details) (USD $) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2011 | Jun. 30, 2010 | Jun. 30, 2011 | Jun. 30, 2010 | Dec. 31, 2010
Derivative instruments [Abstract] |  |  |  |  |
Forward notional volumes of natural gas swap agreements for derivative instruments not designated as hedging instruments in MMBtu's | 676,000 |  | 676,000 |  |
Change in fair value of derivative instruments not designated as hedging instruments | $ 1,900,000 | $ 3,900,000 | $ 8,500,000 | $ 9,000,000 |
Derivative instruments with credit-risk-related contingent features, net liability position, aggregate fair value | 900,000 |  | 900,000 |  |
Aggregate Fair Value for Cascade and/or Intermountain of Assets Needed for Immediate Settlement if credit-risk-related contingent features were triggered | 900,000 |  | 900,000 |  |
Nonmonetary Notional Forward Amount of natural gas swap and collar agreements in MMBtu, Derivative Instruments Designated as cash flow hedging Instruments | 23,300,000 |  | 23,300,000 |  |
Nonmonetary Notional forward Amount of natural gas basis swap agreements in MMBtu, Derivative Instruments Designated as cash flow hedging Instruments | 12,900,000 |  | 12,900,000 |  |
Nonmonetary Notional forward Amount of oil swap, collar and/or put agreements in Bbl, Derivative Instruments Designated as cash flow hedging Instruments | 3,700,000 |  | 3,700,000 |  |
Oil call option agreement with total forward notional volumes (in Bbl) | 184,000 |  | 184,000 |  |
Gain on the derivative instrument that did not qualify for hedge accounting reported in operating revenues | 1,900,000 |  | 179,000 |  |
Maximum Length of Time Hedged in swap, collar and/or put cash flow hedge agreements in months |  |  | 30 |  |
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months from AOCI into earnings |  |  | (2,300,000) |  |
Derivative instruments with credit-risk-related contingent features, Net Liability Position, Aggregate Fair Value for Fidelity | 24,500,000 |  | 24,500,000 |  |
Assets Needed for Immediate Settlement if credit-risk-related contingent feature triggered, Aggregate Fair Value for Fidelity | 24,500,000 |  | 24,500,000 |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |
Asset Derivatives Designated as Hedges | 20,305,000 | 33,456,000 | 20,305,000 | 33,456,000 | 19,227,000
Asset Derivatives Not Designated as Hedges | 194,000 | 0 | 194,000 | 0 | 0
Total Asset Derivatives | 20,499,000 | 33,456,000 | 20,499,000 | 33,456,000 | 19,227,000
Liability Derivatives Designated as Hedges | 24,515,000 | 1,961,000 | 24,515,000 | 1,961,000 | 21,552,000
Liability Derivatives Not Designated as Hedges | 906,000 | 18,897,000 | 906,000 | 18,897,000 | 9,359,000
Total Liability Derivatives | 25,421,000 | 20,858,000 | 25,421,000 | 20,858,000 | 30,911,000
Other Assets [Member] |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |
Asset Derivatives Designated as Hedges | 6,265,000 | 8,524,000 | 6,265,000 | 8,524,000 | 4,104,000
Asset Derivatives Not Designated as Hedges | 0 | 0 | 0 | 0 | 0
Other Liabilities [Member] |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |
Liability Derivatives Designated as Hedges | 6,735,000 | 0 | 6,735,000 | 0 | 6,483,000
Liability Derivatives Not Designated as Hedges | 0 | 698,000 | 0 | 698,000 | 0
Commodity derivative instruments - current assets [Member] |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |
Asset Derivatives Designated as Hedges | 14,040,000 | 24,932,000 | 14,040,000 | 24,932,000 | 15,123,000
Asset Derivatives Not Designated as Hedges | 194,000 | 0 | 194,000 | 0 | 0
Commodity derivative instruments - current liabilities [Member] |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |
Liability Derivatives Designated as Hedges | 17,780,000 | 1,961,000 | 17,780,000 | 1,961,000 | 15,069,000
Liability Derivatives Not Designated as Hedges | $ 906,000 | $ 18,199,000 | $ 906,000 | $ 18,199,000 | $ 9,359,000

X
- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 + Details
Name: | invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix: | invest
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The aggregate fair value of assets needed to immediately settle the derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period for cash flow hedging instruments + Details
Name: | mdu_AssetsNeededForImmediateSettlementAggregateFairValueForCashFlowHedingInstruments
Namespace Prefix: | mdu
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The change in fair value of the derivative instruments not designated as hedging instruments for the period. + Details
Name: | mdu_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsChangeInFairValue
Namespace Prefix: | mdu
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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 cash flow hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain or loss on that instrument. + Details
Name: | mdu_DerivativeNetLiabilityPositionAggregateFairValueForCashFlowHedgingInstruments
Namespace Prefix: | mdu
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Forward notional volumes of natural gas swap agreements for derivative instruments not designated as hedging instruments in MMBtu's + Details
Name: | mdu_ForwardNotionalVolumesOnNaturalGasSwapAgreementsForDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsInMillionMmbtus
Namespace Prefix: | mdu
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nonmonetary Notional Forward Amount of natural gas swap and collar agreements in MMBtu, Derivative Instruments Designated as cash flow hedging Instruments + Details
Name: | mdu_NonmonetaryNotionalAmountOfNaturalGasSwapAndCollarAgreementsInMillionMmbtuDerivativeInstrumentsDesignatedAsCashFlowHedgingInstruments
Namespace Prefix: | mdu
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nonmonetary Notional forward Amount of natural gas basis swap agreements in MMBtu, Derivative Instruments Designated as cash flow hedging Instruments + Details
Name: | mdu_NotionalForwardAmountOfCashFlowHedgeInstrumentsNaturalGasBasisSwaps
Namespace Prefix: | mdu
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nonmonetary Notional forward Amount of oil swap, collar and/or put agreements in Bbl, Derivative Instruments Designated as cash flow hedging Instruments + Details
Name: | mdu_NotionalForwardAmountOfCashFlowHedgeInstrumentsOilSwapsAndCollars
Namespace Prefix: | mdu
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The aggregate fair value of assets needed to immediately settle the 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44D -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_AssetsNeededForImmediateSettlementAggregateFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6887037&loc=d3e80748-113994 + Details
Name: | us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative asset or group of derivative assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13495-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeAssetFairValueNet
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract
Namespace Prefix: | us-gaap
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of gain recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5618551-113959 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_DerivativeInstrumentsGainRecognizedInIncome
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Aggregate fair value of all derivative liabilities designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative liability or group of derivative liabilities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13495-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_DerivativeLiabilityFairValueNet
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4H -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44D -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_DerivativeNetLiabilityPositionAggregateFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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. + Details
Name: | us-gaap_DerivativesFairValueLineItems
Namespace Prefix: | us-gaap
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(3) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6887037&loc=d3e80748-113994 + Details
Name: | us-gaap_MaximumLengthOfTimeHedgedInCashFlowHedge
Namespace Prefix: | us-gaap
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of all derivative assets not designated as a hedging instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAssetsAtFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of all derivative liabilities not designated as a hedging instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611 + Details
Name: | us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsLiabilitiesAtFairValue
Namespace Prefix: | us-gaap
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant