XML 79 R72.htm IDEA: XBRL DOCUMENT v2.4.1.9

Derivative Instruments Subject to master netting agreements (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative instruments [Line Items]
Derivative asset, fair value, gross asset	$ 18,335us-gaap_DerivativeFairValueOfDerivativeAsset	$ 1,950us-gaap_DerivativeFairValueOfDerivativeAsset
Derivative liability, fair value, gross liability	0us-gaap_DerivativeFairValueOfDerivativeLiability	7,483us-gaap_DerivativeFairValueOfDerivativeLiability
Commodity derivative instruments assets [Member]
Derivative instruments [Line Items]
Derivative asset, fair value, gross asset	18,335us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember	1,950us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember
Gross amount not offset	0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember	(1,950)mdu_DerivativeLiabilityFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember
Derivative asset, fair value, net	18,335us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember	0us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativeInstrumentsAssetsMember
Total assets [Member]
Derivative instruments [Line Items]
Derivative asset, fair value, gross asset	18,335us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember	1,950us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember
Gross amount not offset	0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember	(1,950)mdu_DerivativeLiabilityFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember
Derivative asset, fair value, net	18,335us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember	0us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_TotalAssetsMember
Commodity derivatives - liabilities [Member]
Derivative instruments [Line Items]
Derivative liability, fair value, gross liability		7,483us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativesLiabilitiesMember
Gross amount not offset		(1,950)mdu_DerivativeAssetFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativesLiabilitiesMember
Derivative liability, fair value, net		5,533us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_CommodityDerivativesLiabilitiesMember
Total liabilities [Member]
Derivative instruments [Line Items]
Derivative liability, fair value, gross liability		7,483us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_BalanceSheetLocationAxis = mdu_TotalLiabilitiesMember
Gross amount not offset		(1,950)mdu_DerivativeAssetFairValueGrossAmountNotOffset / us-gaap_BalanceSheetLocationAxis = mdu_TotalLiabilitiesMember
Derivative liability, fair value, net		$ 5,533us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral / us-gaap_BalanceSheetLocationAxis = mdu_TotalLiabilitiesMember

X

- Definition

The gross amount as of the balance sheet date of the fair value of derivative assets that in accordance with the entity's accounting policy were not offset against the derivative liability under a master netting arrangement.

+ References

No definition available.

+ Details

Name:	mdu_DerivativeAssetFairValueGrossAmountNotOffset
Namespace Prefix:	mdu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The gross amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy were not offset against the derivative asset under a master netting arrangement.

+ References

No definition available.

+ Details

Name:	mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
Namespace Prefix:	mdu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226006-175313



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226006-175313



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=mdu_CommodityDerivativeInstrumentsAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=mdu_CommodityDerivativesLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=mdu_TotalAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=mdu_TotalLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: