XML 106 R119.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Income resulting from oil and natural gas producing activites (Details 3) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Revenues: |  |  |  |  |  |
Sales to affiliates | $ 47,045,000 us-gaap_ResultsOfOperationsSalesOrTransfersToEntitysOtherOperations |  | $ 45,099,000 us-gaap_ResultsOfOperationsSalesOrTransfersToEntitysOtherOperations |  | $ 35,966,000 us-gaap_ResultsOfOperationsSalesOrTransfersToEntitysOtherOperations |
Sales to external customers | 468,668,000 us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises |  | 497,018,000 us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises |  | 379,647,000 us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises |
Realized gain on commodity derivatives | 8,458,000 us-gaap_ResultsOfOperationsRevenueOther |  | 173,000 us-gaap_ResultsOfOperationsRevenueOther |  | 33,628,000 us-gaap_ResultsOfOperationsRevenueOther |
Unrealized (gain) loss on commodity derivatives | 23,400,000 us-gaap_UnrealizedGainLossOnCommodityContracts |  | (6,267,000)us-gaap_UnrealizedGainLossOnCommodityContracts |  | (624,000)us-gaap_UnrealizedGainLossOnCommodityContracts |
Production costs | 146,793,000 us-gaap_ResultsOfOperationsProductionOrLiftingCosts |  | 144,136,000 us-gaap_ResultsOfOperationsProductionOrLiftingCosts |  | 134,795,000 us-gaap_ResultsOfOperationsProductionOrLiftingCosts |
Depreciation, depletion and amortization | 193,944,000 us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions | [1] | 182,352,000 us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions | [1] | 157,078,000 us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions | [1]
Write-downs of oil and natural gas properties | 0 us-gaap_ResultsOfOperationsImpairmentOfOilAndGasProperties |  | 0 us-gaap_ResultsOfOperationsImpairmentOfOilAndGasProperties |  | 391,800,000 us-gaap_ResultsOfOperationsImpairmentOfOilAndGasProperties |
Pretax income (loss) | 206,834,000 us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes |  | 209,535,000 us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes |  | (235,056,000)us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes |
Income tax expense (benefit) | 75,483,000 us-gaap_ResultsOfOperationsIncomeTaxExpense |  | 75,836,000 us-gaap_ResultsOfOperationsIncomeTaxExpense |  | (88,612,000)us-gaap_ResultsOfOperationsIncomeTaxExpense |
Results of operations for producing activities | 131,351,000 us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts |  | 133,699,000 us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts |  | (146,444,000)us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts |
Accretion of discount for asset retirement obligations oil and gas | $ 3,500,000 mdu_AccretionOfDiscountForAssetRetirementObligationsOilAndGas |  | $ 3,600,000 mdu_AccretionOfDiscountForAssetRetirementObligationsOilAndGas |  | $ 3,300,000 mdu_AccretionOfDiscountForAssetRetirementObligationsOilAndGas |
[1] | Includes accretion of discount for asset retirement obligations of $3.5 million, $3.6 million and $3.3 million for the years ended December 31, 2014, 2013 and 2012, respectively, as discussed in Note 10.

X
- Definition Accretion of discount for asset retirement obligations oil and gas. + References No definition available. + Details
Name: | mdu_AccretionOfDiscountForAssetRetirementObligationsOilAndGas
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Depreciation, depletion and amortization, and valuation provisions (impairments) related to oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 + Details
Name: | us-gaap_ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition Costs related to the impairment of oil and gas properties. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10.(c)(3)(ii)(A)(1)) -URI http://asc.fasb.org/extlink&oid=27015464&loc=d3e511914-122862 + Details
Name: | us-gaap_ResultsOfOperationsImpairmentOfOilAndGasProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Income before income taxes for oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 + Details
Name: | us-gaap_ResultsOfOperationsIncomeBeforeIncomeTaxes
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Income tax expense for oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62259-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 + Details
Name: | us-gaap_ResultsOfOperationsIncomeTaxExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The results of operations for oil and gas producing activities, excluding corporate overhead and interest costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 26 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62299-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 + Details
Name: | us-gaap_ResultsOfOperationsOilAndGasProducingActivitiesNetIncomeExcludingCorporateOverheadAndInterestCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Production (lifting) costs from oil and gas producing activities, including but not limited to lease operating expense, production and ad valorem taxes, and transportation expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 + Details
Name: | us-gaap_ResultsOfOperationsProductionOrLiftingCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Other revenues from oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62246-109447 + Details
Name: | us-gaap_ResultsOfOperationsRevenueOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sales or transfers to the enterprises other operations from oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62246-109447 + Details
Name: | us-gaap_ResultsOfOperationsSalesOrTransfersToEntitysOtherOperations
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sales revenue to unaffiliated enterprises from oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62246-109447 + Details
Name: | us-gaap_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open agreements to purchase or sell mineral resources, energy, and agricultural products at some future point held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
Name: | us-gaap_UnrealizedGainLossOnCommodityContracts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration