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Company's Liability for Environmental Obligations (Detail) - USD ($) $ in Millions | 9 Months Ended |  |  |
--- | --- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Dec. 31, 2015 | Sep. 30, 2015
Environmental Exit Cost [Line Items] |  |  |  |  |
Total Balance at Beginning of period | $ 2.8 | $ 5.5 |  |  |
Additions | 0.9 | 1.9 |  |  |
Less: Payments / Reductions | 0.7 | 1.9 |  |  |
Total Balance at End of period | 3.0 | 5.5 |  |  |
Less: Current Portion |  |  | $ 0.3 | $ 1.3 | $ 5.0
Noncurrent Balance |  |  | 2.7 | 1.5 | 0.5
Total Balance at End of period | 3.0 | 5.5 | 3.0 | 2.8 | 5.5
Fitchburg Gas and Electric Light Company |  |  |  |  |
Environmental Exit Cost [Line Items] |  |  |  |  |
Total Balance at Beginning of period | 1.2 | 1.9 |  |  |
Less: Payments / Reductions | 0.1 | 0.3 |  |  |
Total Balance at End of period | 1.1 | 1.6 |  |  |
Less: Current Portion |  |  | 0.1 |  | 1.6
Noncurrent Balance |  |  | 1.0 |  |
Total Balance at End of period | 1.1 | 1.6 | 1.1 | 1.2 | 1.6
Northern Utilities Inc |  |  |  |  |
Environmental Exit Cost [Line Items] |  |  |  |  |
Total Balance at Beginning of period | 1.6 | 3.6 |  |  |
Additions | 0.9 | 1.9 |  |  |
Less: Payments / Reductions | 0.6 | 1.6 |  |  |
Total Balance at End of period | 1.9 | 3.9 |  |  |
Less: Current Portion |  |  | 0.2 |  | 3.4
Noncurrent Balance |  |  | 1.7 |  | 0.5
Total Balance at End of period | $ 1.9 | $ 3.9 | $ 1.9 | $ 1.6 | $ 3.9

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 + Details
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- Definition Amount of expense for newly incurred environmental loss contingencies. Includes, but is not limited to, remediation expense and interest accretion. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q2) -URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751 + Details
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