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Common Stock And Preferred Stock (Tables) | 3 Months Ended
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Mar. 31, 2013
Details on Preferred Stock | Details on preferred stock at March 31, 2013, March 31, 2012 and December 31, 2012 are shown below: (Amounts in Millions)
|  | March 31, |  |  | December 31, |
|  | 2013 |  |  | 2012 |  |  | 2012 |
Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |
Unitil Energy Preferred Stock, Non-Redeemable, Non-Cumulative: |  |  |  |  |  |  |  |  |  |  |  |
6.00% Series, $100 Par Value, |  | $ | 0.2 |  |  | $ | 0.2 |  |  | $ | 0.2 |
Fitchburg Preferred Stock, Redeemable, Cumulative: |  |  |  |  |  |  |  |  |  |  |  |
5.125% Series, $100 Par Value |  |  | — |  |  |  | 0.8 |  |  |  | — |
8.00% Series, $100 Par Value |  |  | — |  |  |  | 1.0 |  |  |  | — |
Total Preferred Stock |  | $ | 0.2 |  |  | $ | 2.0 |  |  | $ | 0.2 |

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- Definition Preferred Stock Shares + References No definition available. + Details
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Namespace Prefix: | utl_
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Period Type: | duration