XML 102 R119.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Income resulting from oil and natural gas producing activites (Details 4) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Revenues: |  |  |  |  |  |
Sales to affiliates | $ 35,966,000 |  | $ 93,713,000 |  | $ 115,784,000 |
Sales to external customers | 412,651,000 |  | 359,873,000 |  | 318,565,000 |
Production costs | 134,795,000 |  | 140,606,000 |  | 127,403,000 |
Depreciation, depletion and amortization | 157,078,000 | [1] | 139,539,000 | [1] | 127,266,000 | [1]
Write-downs of oil and natural gas properties | 391,800,000 |  | 0 |  | 0 |
Pretax income (loss) | (235,056,000) |  | 173,441,000 |  | 179,680,000 |
Income tax expense (benefit) | (88,612,000) |  | 63,655,000 |  | 66,293,000 |
Results of operations for producing activities | (146,444,000) |  | 109,786,000 |  | 113,387,000 |
Accretion of discount for asset retirement obligations oil and gas | $ 3,300,000 |  | $ 3,600,000 |  | $ 3,200,000 |
[1] | Includes accretion of discount for asset retirement obligations of $3.3 million, $3.6 million and $3.2 million for the years ended December 31, 2012, 2011 and 2010, 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_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=21918352&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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -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_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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59U -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_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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -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_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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -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_ResultsOfOperationsProductionOrLiftingCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59T -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_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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59T -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_ResultsOfOperationsSalesRevenueToUnaffiliatedEnterprises
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration