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Natural gas costs recoverable or refundable through rate adjustments (Details 10) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Accounting Policies [Abstract] |  |
Minimum period over which natural gas costs greater or less than amounts being recovered become recoverable or refundable through rate adjustments | 12 months |
Maximum period over which natural gas costs greater or less than amounts being recovered become recoverable or refundable through rate adjustments | 28 months |
Natural gas costs refundable | $ 13.2 us-gaap_RefundableGasCosts | $ 16.9 us-gaap_RefundableGasCosts
Natural gas costs recoverable | $ 19.6 us-gaap_DeferredGasCost | $ 12.1 us-gaap_DeferredGasCost

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- Definition Maximum period over which natural gas costs greater or less than amounts being recovered through existing rate schedules become recoverable or refundable through rate adjustments. + References No definition available. + Details
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- Definition Minimum period over which natural gas costs greater or less than amounts being recovered through existing rate schedules become recoverable or refundable through rate adjustments. + References No definition available. + Details
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- Details
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- Definition Carrying amount as of the balance sheet date of capitalized gas costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499739&loc=d3e43603-110378 + Details
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- Definition Gas costs of a regulated entity that are refundable through future rate adjustments. Such costs are a form of a regulatory liabilities and are expected to be refunded in less than one year through rate adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + Details
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