SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
number in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2020
USD ($)
Jun. 30, 2019
Jun. 30, 2020
USD ($)
Jun. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
Jan. 01, 2019
USD ($)
Significant Accounting Policies [Line Items]            
Document Period End Date     Jun. 30, 2020      
Number of natural gas distribution services customers 2.2   2.2      
Segment Reporting, Disclosure of Major Customers 0 0 0 0    
Capital Expenditures Incurred but Not yet Paid     $ 6.9 $ 2.4    
Allowance for Doubtful Accounts, Premiums and Other Receivables $ 12.2   $ 12.2   $ 6.6  
Operating Lease, Right-of-Use Asset           $ 32.0
Operating Lease, Liability           $ 32.0
Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block]    
Accounts Receivable - Accounts receivable represent valid claims against nonaffiliated customers for natural gas sold or services rendered, net of allowances for doubtful accounts. We assess the creditworthiness of our customers. Those customers who do not meet minimum standards may be required to provide security, including deposits and other forms of collateral, when appropriate and allowed by our tariffs. With approximately 2.2 million customers across three states, we are not exposed materially to a concentration of credit risk. We maintain an allowance for doubtful accounts based upon factors surrounding the credit risk of customers, historical trends, consideration of the current environment and other information. We recover natural gas costs related to accounts written off when they are deemed uncollectible through the purchased-gas cost adjustment mechanisms in each of our jurisdictions. At June 30, 2020 and December 31, 2019, our allowance for doubtful accounts was $12.2 million and $6.6 million, respectively.