XML 83 R58.htm IDEA: XBRL DOCUMENT v2.4.0.8

Business segment data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 1,042,853	$ 931,604
Intersegment operating revenues	0	0
Earnings on common stock	56,491	56,344
Regulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	491,541	424,124
Intersegment operating revenues	18,276	18,718
Earnings on common stock	42,645	44,673
Unregulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	551,312	507,480
Intersegment operating revenues	30,346	17,498
Earnings on common stock	14,197	11,671
Electric [Member] | Regulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	73,647	64,654
Intersegment operating revenues	0	0
Earnings on common stock	11,033	9,825
Natural gas distribution [Member] | Regulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	374,233	331,754
Intersegment operating revenues	0	0
Earnings on common stock	27,263	32,518
Pipeline and energy services [Member] | Regulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	43,661	27,716
Intersegment operating revenues	18,276	18,718
Earnings on common stock	4,349	2,330
Exploration and production [Member] | Unregulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	116,669	115,363
Intersegment operating revenues	20,867	9,812
Earnings on common stock	20,939	20,284
Construction materials and contracting [Member] | Unregulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	164,423	161,977
Intersegment operating revenues	4,017	4,294
Earnings on common stock	(23,574)	(20,582)
Construction services [Member] | Unregulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	269,892	229,806
Intersegment operating revenues	3,738	1,574
Earnings on common stock	16,568	11,664
Other [Member] | Unregulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues	328	334
Intersegment operating revenues	1,724	1,818
Earnings on common stock	264	305
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment operating revenues	(48,622)	(36,216)
Earnings on common stock	$ (351)	$ 0

X

- Definition

Intersegment operating revenues.

+ References

No definition available.

+ Details

Name:	mdu_Intersegmentoperatingrevenues
Namespace Prefix:	mdu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1377-109256

+ Details

Name:	us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

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