|**Accounts Receivable**              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
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|**Accounts Receivable [Abstract]**   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Accounts Receivable                  | Note 5 –Accounts ReceivableDecember 31,20192018Billed utility revenue$69,205$68,347Other5,2854,39274,49072,739Less allowance for doubtful accounts7,3536,914Net accounts receivable$67,137$65,825The Company’s utility customers are located principally in the following states:47% in Pennsylvania,15% in Ohio,10% in North Carolina,8% in Texas, and8% in Illinois.  No single customer accounted for more than one percent of the Company's regulated operating revenues during the years ended December 31, 2019, 2018, and 2017.  The following table summarizes the changes in the Company’s allowance for doubtful accounts:201920182017Balance at January 1,$6,914$7,071$7,095Amounts charged to expense5,3065,3054,986Accounts written off(5,980)(6,587)(6,135)Recoveries of accounts written off1,1131,1251,125Balance at December 31,$7,353$6,914$7,071
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|                                     | December 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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|Billed utility revenue               | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Other                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
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|Less allowance for doubtful accounts |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Net accounts receivable              | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
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|                                     | 2019                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|Balance at January 1,                | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Amounts charged to expense           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Accounts written off                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Recoveries of accounts written off   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Balance at December 31,              | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

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