Accounts Receivable (Narrative) (Details)	Dec. 31, 2019
Pennsylvania [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
utility customers by geographic operating segment, percentage	47.00%
Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
utility customers by geographic operating segment, percentage	15.00%
North Carolina [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
utility customers by geographic operating segment, percentage	10.00%
Texas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
utility customers by geographic operating segment, percentage	8.00%
Illinois [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
utility customers by geographic operating segment, percentage	8.00%