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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
number in Millions, $ in Millions
3 Months Ended
Mar. 31, 2017
USD ($)
Mar. 31, 2016
Significant Accounting Policies [Line Items]    
Number of natural gas distribution services customers 2  
Segment Reporting, Disclosure of Major Customers 0 0
Excess tax benefit related to the share-based compensation provision $ 5.2  
Operating loss carryforward related to the share-based compensation provision 11.0  
Prior period cash flow reclass related to the share-based compensation provision $ 8.8