Long-Term Debt and Short-Term Borrowings, Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Long-term Debt [Abstract]
Long-term debt	$ 92,833	$ 87,488
Less discount on issuance of long-term debt	(215)	(226)
Less unamortized debt issuance costs	(2,476)	(2,609)
Less current maturities	(44)	(44)
Long-term portion	90,098	84,609
10.17% Senior Notes, Series A, due 2019 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 6,000	6,000
Interest rate	10.17%
9.60% Senior Notes, Series B, due 2019 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 5,000	5,000
Interest rate	9.60%
1.00% Pennvest Note, due 2019 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 74	118
Interest rate	1.00%
10.05% Senior Notes, Series C, due 2020 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 6,500	6,500
Interest rate	10.05%
8.43% Senior Notes, Series D, due 2022 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 7,500	7,500
Interest rate	8.43%
Variable Rate Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Bonds Series 2008A due 2029 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 12,000	12,000
4.75% York County Industrial Development Authority Revenue Bonds, series 2006, due 2036 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 10,500	10,500
Interest rate	4.75%
4.50% Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Refunding Bonds, Series 2014, due 2038 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 14,870	14,870
Interest rate	4.50%
5.00% Monthly Senior Notes, Series 2010A, due 2040 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 15,000	15,000
Interest rate	5.00%
4.00% - 4.50% York County Industrial Development Authority Exempt Facilities Revenue Bonds, Series 2015, due 2029 - 2045 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 10,000	10,000
4.00% - 4.50% York County Industrial Development Authority Exempt Facilities Revenue Bonds, Series 2015, due 2029 - 2045 [Member] \| Minimum [Member]
Long-term Debt [Abstract]
Interest rate	4.00%
4.00% - 4.50% York County Industrial Development Authority Exempt Facilities Revenue Bonds, Series 2015, due 2029 - 2045 [Member] \| Maximum [Member]
Long-term Debt [Abstract]
Interest rate	4.50%
Committed Line of Credit, due 2019 [Member]
Long-term Debt [Abstract]
Long-term debt	$ 5,389	$ 0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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