Rendering

Component: (Network and Table)
Network
2407402 - Disclosure - Asset Retirement Obligations (Details)
(http://www.mdu.com/role/AssetRetirementObligationsDetails)
Table(Implied)
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0000067716 (http://www.sec.gov/CIK)
Asset Retirement Obligation [Abstract]Period [Axis]
2016-01-01 - 2016-12-31
2015-01-01 - 2015-12-31
Asset Retirement Obligation [Abstract]
 
 
Asset retirement obligation [Roll Forward]
 
 
Balance, beginning of period
242,224,000  
27,211,000  
Liabilities incurred
15,114,000  
2,751,000  
Liabilities settled
(4,338,000) 
(1,708,000) 
Accretion expense
13,918,000  
2,134,000  
Revisions in estimates
48,052,000  
211,836,000  
Balance, end of period
314,970,000  
 
242,224,000