Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

- Definition

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.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
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-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
-Paragraph 1
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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-Paragraph 1
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Debt (Details) - USD ($) $ in Thousands	9 Months Ended
Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Debt [Abstract]
Total long-term debt	$ 92,913		$ 92,833
Less discount on issuance of long-term debt	(206)		(215)
Less unamortized debt issuance costs	(2,377)		(2,476)
Less current maturities	(11,041)		(44)
Long-term portion	79,289		90,098
10.17% Senior Notes, Series A, due 2019 [Member]
Debt [Abstract]
Total long-term debt	$ 6,000		6,000
Interest rate	10.17%
9.60% Senior Notes, Series B, due 2019 [Member]
Debt [Abstract]
Total long-term debt	$ 5,000		5,000
Interest rate	9.60%
1.00% Pennvest Note, due 2019 [Member]
Debt [Abstract]
Total long-term debt	$ 41		74
Interest rate	1.00%
10.05% Senior Notes, Series C, due 2020 [Member]
Debt [Abstract]
Total long-term debt	$ 6,500		6,500
Interest rate	10.05%
8.43% Senior Notes, Series D, due 2022 [Member]
Debt [Abstract]
Total long-term debt	$ 7,500		7,500
Interest rate	8.43%
Variable Rate Pennsylvania Economic Development Financing Authority Exempt Facilities Revenue Refunding Bonds, Series 2008A, due 2029 [Member]
Debt [Abstract]
Total long-term debt	$ 12,000		12,000
4.75% York County Industrial Development Authority Revenue Bonds, series 2006, due 2036 [Member]
Debt [Abstract]
Total 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]
Debt [Abstract]
Total long-term debt	$ 14,870		14,870
Interest rate	4.50%
5.00% Monthly Senior Notes, Series 2010A, due 2040 [Member]
Debt [Abstract]
Total 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]
Debt [Abstract]
Total 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] \| Maximum [Member]
Debt [Abstract]
Interest rate	4.50%
4.00% - 4.50% York County Industrial Development Authority Exempt Facilities Revenue Bonds, Series 2015, due 2029 - 2045 [Member] \| Minimum [Member]
Debt [Abstract]
Interest rate	4.00%
Committed Lines of Credit, due 2020 [Member]
Debt [Abstract]
Total long-term debt	$ 5,502		$ 5,389
First Line of Credit [Member]
Debt [Abstract]
Renewed line of credit		$ 13,000
Maturity date	May 31, 2020
Second Line of Credit [Member]
Debt [Abstract]
Renewed line of credit		11,000
Maturity date	May 31, 2020
Third Line of Credit [Member]
Debt [Abstract]
Renewed line of credit		7,500
Maturity date	Jun. 30, 2020
Third Line of Credit [Member] \| LIBOR [Member]
Debt [Abstract]
Basis adjustment	1.15%
Fourth Line of Credit [Member]
Debt [Abstract]
Renewed line of credit		$ 10,000
Maturity date	Sep. 30, 2019