XML 45 R23.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Regulatory Assets and Reclassification From the Regulatory Asset into Purchased Gas (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Natural Gas Future Contract |  |  |  |  |  |
Regulatory Assets [Line Items] |  |  |  |  |  |
Gain (loss) recognized in Regulatory Assets | $ (0.3) | $ 0.9 | $ 1.1 |  | $ 1.5 |
Gas Purchase Costs |  |  |  |  |  |
Regulatory Assets [Line Items] |  |  |  |  |  |
Loss reclassification into unaudited Consolidated Statement of Earnings |  |  | $ 2.2 | [1] | $ 1.0 | [1]
[1] | These amounts are offset in the unaudited Consolidated Statements of Earnings with Accrued Revenue and therefore there is no effect on earnings.

X
- Definition Loss included in earnings for the period from the change in fair value of derivative instruments not designated as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph b(1)(b) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RegulatoryAssetLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Derivative Instruments Gain Loss Recognized In Regulatory Assets + References No definition available. + Details
Name: | utl_DerivativeInstrumentsGainLossRecognizedInRegulatoryAssets
Namespace Prefix: | utl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration