XML 137 R49.htm IDEA: XBRL DOCUMENT v2.4.1.9

Inventories and natural gas in storage (Details 2) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Aggregates held for resale	$ 108,161,000mdu_AggregatesHeldForResaleInventory	$ 101,568,000mdu_AggregatesHeldForResaleInventory
Materials and supplies	65,683,000us-gaap_InventoryRawMaterialsAndSupplies	69,808,000us-gaap_InventoryRawMaterialsAndSupplies
Asphalt oil	42,135,000mdu_AsphaltOilInventory	38,099,000mdu_AsphaltOilInventory
Merchandise for resale	24,420,000us-gaap_InventoryFinishedGoods	21,720,000us-gaap_InventoryFinishedGoods
Natural gas in storage (current)	19,302,000us-gaap_EnergyRelatedInventoryNaturalGasInStorage	16,417,000us-gaap_EnergyRelatedInventoryNaturalGasInStorage
Other	41,110,000us-gaap_OtherInventoryNetOfReserves	34,779,000us-gaap_OtherInventoryNetOfReserves
Total	300,811,000us-gaap_InventoryNet	282,391,000us-gaap_InventoryNet
Natural gas in storage noncurrent	$ 49,300,000mdu_NaturalGasInStorageNoncurrent	$ 48,300,000mdu_NaturalGasInStorageNoncurrent

X

- Definition

Aggregated amount of aggregates held for resale. This amount is net of valuation reserves and adjustments.

+ References

No definition available.

+ Details

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

X

- Definition

Aggregated amount of asphalt oil inventory. This amount is net of valuation reserves and adjustments.

+ References

No definition available.

+ Details

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

X

- Definition

Carrying amount as of the balance sheet date of natural gas in storage, which largely represents the cost of gas required to maintain pressure levels for normal operating purposes, and deemed to be noncurrent asset.

+ References

No definition available.

+ Details

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

X

- Details

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

X

- Definition

Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

+ Details

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

X

- Definition

Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

X

- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

+ Details

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

X

- Definition

Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(4),(5))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

X

- Definition

Carrying amount, net of valuation reserves and allowances, as of the balance sheet date of inventories not otherwise specified in the taxonomy.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 5.BB)

-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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