XML 31 R52.htm IDEA: XBRL DOCUMENT v2.4.1.9
Subject to master netting agreements (Details 4) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Derivative instruments [Line Items]      
Derivative asset, fair value, gross asset $ 7,127us-gaap_DerivativeFairValueOfDerivativeAsset $ 18,335us-gaap_DerivativeFairValueOfDerivativeAsset $ 330us-gaap_DerivativeFairValueOfDerivativeAsset
Derivative liability fair value gross liability 0us-gaap_DerivativeFairValueOfDerivativeLiability 0us-gaap_DerivativeFairValueOfDerivativeLiability 12,186us-gaap_DerivativeFairValueOfDerivativeLiability
Commodity derivative instruments assets [Member]      
Derivative instruments [Line Items]      
Derivative asset, fair value, gross asset 7,127us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
18,335us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
330us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
Gross amount not offset 0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
(330)mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
Derivative asset, fair value, net 7,127us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativeInstrumentsAssetsMember
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 7,127us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
18,335us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
330us-gaap_DerivativeFairValueOfDerivativeAsset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
Gross amount not offset 0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
0mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
(330)mdu_DerivativeLiabilityFairValueGrossAmountNotOffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
Derivative asset, fair value, net 7,127us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalAssetsMember
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     12,186us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativesLiabilitiesMember
Gross amount not offset     (330)mdu_Derivativeassetfairvaluegrossamountnotoffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativesLiabilitiesMember
Derivative liability, fair value, net     11,856us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
/ us-gaap_BalanceSheetLocationAxis
= mdu_CommodityDerivativesLiabilitiesMember
Total liabilities [Member]      
Derivative instruments [Line Items]      
Derivative liability fair value gross liability     12,186us-gaap_DerivativeFairValueOfDerivativeLiability
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalLiabilitiesMember
Gross amount not offset     (330)mdu_Derivativeassetfairvaluegrossamountnotoffset
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalLiabilitiesMember
Derivative liability, fair value, net     $ 11,856us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
/ us-gaap_BalanceSheetLocationAxis
= mdu_TotalLiabilitiesMember