XML 72 R64.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Commitment and contingencies variable interest entities (Details 4) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 | Mar. 31, 2013
--- | --- | --- | ---
Dakota Prairie Refining, LLC [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Percent of ownership | 50.00% |  |
Total project costs | $ 300,000,000 |  |
Portion of capital commitment | 150,000,000 |  |
Partner portion of capital commitment | 75,000,000 |  |
Excess capital commitments | 300,000,000 |  |
Project cost estimate | 350,000,000 |  |
Term loan for project debt financing | 75,000,000 |  |
Dakota Prairie Refining, LLC [Member] | Cash and Cash Equivalents [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, assets | 22,996,000 | 4,774,000 | 10,793,000
Dakota Prairie Refining, LLC [Member] | Other current assets [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, assets | 1,135,000 | 26,000 | 0
Dakota Prairie Refining, LLC [Member] | Total current assets [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, assets | 24,131,000 | 4,800,000 | 10,793,000
Dakota Prairie Refining, LLC [Member] | Net property, plant and equipment [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, assets | 207,260,000 | 172,073,000 | 27,356,000
Dakota Prairie Refining, LLC [Member] | Total assets [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, assets | 231,391,000 | 176,873,000 | 38,149,000
Dakota Prairie Refining, LLC [Member] | Long-term debt due within one year [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 3,000,000 | 3,000,000 | 0
Dakota Prairie Refining, LLC [Member] | Accounts payable [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 16,103,000 | 8,904,000 | 10,948,000
Dakota Prairie Refining, LLC [Member] | Taxes Payable [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 113,000 | 5,000 | 0
Dakota Prairie Refining, LLC [Member] | Accrued Compensation [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 164,000 | 26,000 | 0
Dakota Prairie Refining, LLC [Member] | Other accrued liabilities [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 580,000 | 461,000 | 0
Dakota Prairie Refining, LLC [Member] | Total current liabilities [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 19,960,000 | 12,396,000 | 10,948,000
Dakota Prairie Refining, LLC [Member] | Long-term debt [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 72,000,000 | 72,000,000 | 0
Dakota Prairie Refining, LLC [Member] | Total liabilities [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Limited liability entity, consolidated, carrying amount, liabilities | 91,960,000 | 84,396,000 | 10,948,000
Fuel contract [Member] |  |  |
Variable Interest Entities [Line Items] |  |  |
Variable interest entity, reporting entity involvement, maximum loss exposure, amount | $ 8,200,000 |  |

X
- Definition Excess capital commitments above this amount will be shared equally. + References No definition available. + Details
Name: | mdu_ExcessCapitalCommitments
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Partner portion of capital commitment. + References No definition available. + Details
Name: | mdu_PartnerPortionOfCapitalCommitment
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percent of ownership. + References No definition available. + Details
Name: | mdu_PercentOfOwnership
Namespace Prefix: | mdu_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Portion of capital commitment. + References No definition available. + Details
Name: | mdu_PortionOfCapitalCommitment
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Project cost estimate + References No definition available. + Details
Name: | mdu_ProjectCostEstimate
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of term loan entered into to finance the project. + References No definition available. + Details
Name: | mdu_TermLoanForProjectDebtFinancing
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total project costs. + References No definition available. + Details
Name: | mdu_Totalprojectcosts
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5710-111685 + Details
Name: | us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5710-111685 + Details
Name: | us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5728-111685 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5747-111685 + Details
Name: | us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant