XML 78 R53.htm IDEA: XBRL DOCUMENT v2.4.0.8

Goodwill (Details 5)	3 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]
Fair value inputs discount rate, range bottom	5.00%
Fair value inputs, discount rate, range top	10.00%
Long-term growth rate projections	3.00%

X

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value, range top.

+ References

No definition available.

+ Details

Name:	mdu_FairValueDiscountRateRangeTop
Namespace Prefix:	mdu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value, bottom.

+ References

No definition available.

+ Details

Name:	mdu_FairValueInputsDiscountRatesRangeBottom
Namespace Prefix:	mdu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Definition

Percentage of assumed long-term growth in revenues, used as an input to measure fair value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsLongTermRevenueGrowthRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration