XML 89 R17.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Preferred Stocks | 12 Months Ended
--- | ---
Dec. 31, 2011
Preferred Stocks [Abstract] |
Preferred Stocks | Preferred Stocks Preferred stocks at December 31 were as follows:
| 2011 |  |  | 2010 |
| (Dollars in thousands)
Authorized: |  |  |
Preferred - |  |  |
500,000 shares, cumulative, par value $100, issuable in series |  |  |
Preferred stock A - |  |  |
1,000,000 shares, cumulative, without par value, issuable in series (none outstanding) |  |  |
Preference - |  |  |
500,000 shares, cumulative, without par value, issuable in series (none outstanding) |  |  |
Outstanding: |  |  |
4.50% Series - 100,000 shares | $ | 10,000 |  |  | $ | 10,000 |
4.70% Series - 50,000 shares | 5,000 |  |  | 5,000 |
Total preferred stocks | $ | 15,000 |  |  | $ | 15,000 |
For the years 2011, 2010 and 2009, dividends declared on the 4.50% Series and 4.70% Series preferred stocks were $4.50 and $4.70 per share, respectively. The 4.50% Series and 4.70% Series preferred stocks outstanding are subject to redemption, in whole or in part, at the option of the Company with certain limitations on 30 days no tice on any quarterly dividend date at a redemption price, plus accrued dividends, of $105 per share and $102 per share, respectively. In the event of a voluntary or involuntary liquidation, all preferred stock series holders are entitled to $100 per share, plus accrued dividends. The affirmative vote of two-thirds of a series of the Company's outstanding preferred stock is necessary for amendments to the Company's charter or bylaws that adversely affect that series; creation of or increase in the amount of authorized stock ranking senior to that series (or an affirmative majority vote where the authorization relates to a new class of stock that ranks on parity with such series); a voluntary liquidation or sale of substantially all of the Company's assets; a merger or consolidation, with certain exceptions; or the partial retirement of that series of preferred stock when all dividends on that series of preferred stock have not been paid. The consent of the holders of a particular series is not required for such corporate actions if the equivalent vote of all outstanding series of preferred stock voting together has consented to the given action and no particular series is affected differently than any other series. Subject to the foregoing, the holders of common stock exclusively possess all voting power. However, if cumulative dividends on preferred stock are in arrears, in whole or in part, for one year, the holders of preferred stock would obtain the right to one vote per share until all dividends in arrears have been paid and current dividends have been declared and set aside.

X
- Details
Name: | mdu_PreferredStocksAbstract
Namespace Prefix: | mdu_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to preferred stock. + References No definition available. + Details
Name: | us-gaap_PreferredStockTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration