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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Regulatory Assets (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | May 25, 2005
Regulatory Assets [Abstract] |  |  |  |
Amortization period of depreciation and salary study expenses | 5 years |  |  |
Goodwill amortization period | 50 years |  |  |
Amortization period of deferred acquisition costs | 20 years |  |  |
Amortization period of deferred franchise costs | 80 years |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | $ 2,393,000 | $ 2,734,000 |  |
Summary of other deferred assets net of amortization [Abstract] |  |  |  |
Debt issuance cost | 2,108,000 | 2,228,000 |  |
Investment in Co Bank | 2,523,000 | 2,294,000 |  |
Other | 565,000 | 620,000 |  |
Other deferred assets | 5,196,000 | 5,142,000 |  |
Stock Compensation Plans [Abstract] |  |  |  |
Number of share authorize under equity compensation plan (in shares) |  |  |  | 500,000
Compensation costs | 108,000 | 120,000 | 111,000 |
Summary of fair value of each option grant is estimated using the Black-Scholes-Merton option pricing model [Abstract] |  |  |  |
Dividend Yield (in hundredths) | 4.18% | 4.00% | 4.20% |
Expected Volatility (in hundredths) | 25.13% | 24.97% | 27.44% |
Risk Free Interest Rate (in hundredths) | 1.87% | 3.12% | 3.38% |
Expected Term | 9 years 5 months 19 days | 8 years 4 months 10 days | 8 years 11 months 19 days |
Base period for calculation of expected dividend yield | 12 months |  |  |
Period for risk free interest rate base on treasury constant maturity rate | 10 years | 10 years | 10 years |
Accounts Receivable [Abstract] |  |  |  |
Expense related to allowance for doubtful accounts | 200,000 | 300,000 |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |
Gross accounts receivable | 5,969,000 | 5,213,000 | 5,324,000 |
Less allowance for doubtful accounts | 241,000 | 216,000 | 230,000 |
Net accounts receivable | 5,728,000 | 4,997,000 | 5,094,000 |
Summary of allowance for doubtful accounts [Abstract] |  |  |  |
Beginning balance | 216,000 | 230,000 | 142,000 |
Allowance adjustments | 215,000 | 262,000 | 370,000 |
Recoveries | 141,000 | 111,000 | 78,000 |
Write off of uncollectible accounts | (331,000) | (387,000) | (360,000) |
Ending balance | 241,000 | 216,000 | 230,000 |
Cash and Cash Equivalents [Abstract] |  |  |  |
Maximum maturity period of temporary cash investments consider as cash equivalents | 3 months |  |  |
Customer accounts receivable - water [Member] |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |
Gross accounts receivable | 3,988,000 | 3,390,000 | 3,161,000 |
Other [Member] |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |
Gross accounts receivable | 1,981,000 | 1,823,000 | 2,163,000 |
2005 Equity Compensation Plan [Member] |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |
Number of share authorize under equity compensation plan (in shares) | 375,000 |  |  |
Mountain Hill [Member] |  |  |  |
Summary of other deferred assets net of amortization [Abstract] |  |  |  |
Other | 400,000 |  |  |
Minimum [Member] |  |  |  |
Other Deferred Assets [Abstract] |  |  |  |
Amortization period of debt issuance costs | 10 years |  |  |
Maximum [Member] |  |  |  |
Other Deferred Assets [Abstract] |  |  |  |
Amortization period of debt issuance costs | 30 years |  |  |
Maryland [Member] |  |  |  |
Regulatory Assets [Abstract] |  |  |  |
Amortization period of regulatory rate proceedings and applications | 5 years |  |  |
Delaware [Member] |  |  |  |
Regulatory Assets [Abstract] |  |  |  |
Amortization period of regulatory rate proceedings and applications | 2 years |  |  |
Postretirement benefit obligation [Member] |  |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | 497,000 | 567,000 |  |
Deferred income taxes [Member] |  |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | 491,000 | 506,000 |  |
Goodwill [Member] |  |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | 340,000 | 348,000 |  |
Deferred acquisition and franchise costs [Member] |  |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | 824,000 | 816,000 |  |
Expense of rate and regulatory proceedings [Member] |  |  |  |
Summary of regulatory assets net of amortization, comprise [Abstract] |  |  |  |
Regulatory assets, net | $ 241,000 | $ 497,000 |  |

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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(c) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.D.2) -URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(b) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(d) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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