Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Estimated employer contributions	$ 1,593,000
Change in Benefit Obligation [Abstract]
Pension benefit obligation beginning of year	31,580,000		26,546,000
Service cost	1,050,000		930,000		777,000
Interest cost	1,288,000		1,391,000		1,335,000
Actuarial loss	1,789,000		3,618,000
Plan amendments	0		92,000		0
Benefit payments	(981,000)		(997,000)
Pension benefit obligation end of year	34,726,000		31,580,000		26,546,000
Change in Plan Assets [Abstract]
Fair value of plan assets beginning of year	19,815,000		19,276,000
Actual return on plan assets	2,239,000		(57,000)
Employer contributions	1,593,000		1,593,000
Benefits paid	(981,000)		(997,000)
Fair value of plan assets end of year	22,666,000		19,815,000		19,276,000
Funded Status of Plans at End of Year	(12,060,000)		(11,765,000)
Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets [Abstract]
Net loss (gain) arising during the period	991,000		5,009,000
Recognized net actuarial loss	(641,000)		(313,000)		(213,000)
Recognized prior service cost	(17,000)		(17,000)		(17,000)
Total changes in regulatory asset during the year	333,000		4,679,000
Amounts recognized in regulatory assets that have not yet been recognized as components of net periodic benefit cost [Abstract]
Net loss	11,802,000		11,451,000
Prior service cost	67,000		85,000
Regulatory asset	11,869,000		11,536,000
Components of Net Periodic Benefit Cost [Abstract]
Service cost	1,050,000		930,000		777,000
Interest cost	1,288,000		1,391,000		1,335,000
Expected return on plan assets	(1,441,000)		(1,334,000)		(1,165,000)
Plan amendments	0		92,000		0
Amortization of loss	641,000		313,000		213,000
Amortization of prior service cost	17,000		17,000		17,000
Rate-regulated adjustment	38,000		184,000		103,000
Net periodic pension expense	1,593,000		1,593,000		1,280,000
Change in defined benefit plan regulatory asset from pension contribution greater (less) than net periodic benefit cost	38,000
Regulatory assets to be reclassified into net periodic benefit cost during the next 12 months [Abstract]
Net loss	694,000
Net prior service cost	10,000
Regulatory assets to be reclassified into net periodic benefit cost during the next 12 months	704,000
Benefit payments expected to be paid for future services [Abstract]
2013	1,174,000
2014	1,267,000
2015	1,488,000
2016	1,524,000
2017	1,524,000
2018-2022	9,419,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Accumulated benefit obligation	31,412,000		28,473,000
Fair value of plan assets	22,666,000		19,815,000		19,276,000
Projected benefit obligation and fair value of plan assets [Abstract]
Projected benefit obligation	34,726,000		31,580,000		26,546,000
Fair value of plan assets	22,666,000		19,815,000		19,276,000
Weighted-average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)	3.75%		4.25%
Rate of compensation increase (in hundredths)	3.00%		3.00%
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate (in hundredths)	4.25%		5.35%		6.00%
Expected long-term return on plan assets (in hundredths)	7.00%		7.00%		7.00%
Rate of compensation increase (in hundredths)	3.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Percentage by which the return on plan assets should exceed the annual rate of inflation (in hundredths)	3.00%
Maximum equity securities holdings in any one company (in hundredths)	5.00%
Minimum number of individual stocks that must be included in the domestic stock portfolio	20
Minimum number of individual stocks that must be included in the international stock portfolio	30
Maximum fixed income securities holdings in any single issuer (in hundredths)	5.00%
Fair values of pension plan assets [Abstract]
Total Plan Assets	22,666,000		19,815,000		19,276,000
Fair value of plan assets invested in Company stock	339,000
Percentage of fair value of plan assets invested in Company stock (in hundredths)	1.50%
Defined Contribution Plan [Abstract]
Maximum elective employee contributions (in hundredths)	15.00%
Company matching contributions (in hundredths)	100.00%
Maximum annual Company contribution for each employee	2,800
Increase in maximum annual Company contribution for each employee	600
Number of employees participating in enhanced feature of plan	3
Company's total contributions to defined contribution plan	244,000		220,000		187,000
Maximum annual Company contribution as a percentage of employee's compensation (in hundredths)	4.00%
Annual Company discretionary contribution	1,200
Deferred Compensation [Abstract]
Present value of future obligations	3,271,000		3,039,000
Total cash value of insurance policies	3,477,000		3,380,000
Company's expenses under deferred compensation plans	358,000		514,000		360,000
Cash and Money Market Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	534,000	[1]	498,000	[1]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	534,000	[1]	498,000	[1]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	534,000	[1]	498,000	[1]
Fair values of pension plan assets [Abstract]
Total Plan Assets	534,000	[1]	498,000	[1]
Common Equity Securities [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	3,974,000	[2]	3,755,000	[2]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	3,974,000	[2]	3,755,000	[2]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	3,974,000	[2]	3,755,000	[2]
Fair values of pension plan assets [Abstract]
Total Plan Assets	3,974,000	[2]	3,755,000	[2]
Common Equity Securities [Member] | Mid cap [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	15.00%
Common Equity Securities [Member] | Small cap [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Common Equity Securities [Member] | International [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	15.00%
Common Equity Securities [Member] | Emerging market [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	5.00%
Equity Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	11,309,000	[3]	9,088,000	[3]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	11,309,000	[3]	9,088,000	[3]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	11,309,000	[3]	9,088,000	[3]
Fair values of pension plan assets [Abstract]
Total Plan Assets	11,309,000	[3]	9,088,000	[3]
U.S. Treasury Obligations [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	355,000		593,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	355,000		593,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	355,000		593,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	355,000		593,000
U.S. Government Agencies [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	806,000		808,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	806,000		808,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	806,000		808,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	806,000		808,000
Corporate and Foreign Bonds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	409,000	[4]	896,000	[4]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	409,000	[4]	896,000	[4]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	409,000	[4]	896,000	[4]
Fair values of pension plan assets [Abstract]
Total Plan Assets	409,000	[4]	896,000	[4]
Fixed Income Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	5,279,000	[5]	4,177,000	[5]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	5,279,000	[5]	4,177,000	[5]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	5,279,000	[5]	4,177,000	[5]
Fair values of pension plan assets [Abstract]
Total Plan Assets	5,279,000	[5]	4,177,000	[5]
Debt Securities [Member] | International [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Debt Securities [Member] | Mortgage-backed securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Debt Securities [Member] | High yield bonds [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Debt Securities [Member] | U.S. Treasury and Agency securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	30.00%
Debt Securities [Member] | U.S. corporate bonds [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	40.00%
Minimum [Member]
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase (in hundredths)			3.50%		4.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Investment performance objectives benchmark period	3 years
Maximum equity securities holding in portfolio per industry (in hundredths)	20.00%
Minimum [Member] | Cash and Money Market Funds [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	0.00%
Minimum [Member] | Common Equity Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	50.00%
Asset allocation of plan assets (in hundredths)	50.00%
Minimum [Member] | Common Equity Securities [Member] | Large cap [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	45.00%
Minimum [Member] | Common Equity Securities [Member] | Inflation hedge [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	5.00%
Minimum [Member] | Debt Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	30.00%
Asset allocation of plan assets (in hundredths)	30.00%
Maximum [Member]
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Rate of compensation increase (in hundredths)			4.00%		5.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Investment performance objectives benchmark period	5 years
Maximum equity securities holding in portfolio per industry (in hundredths)	25.00%
Maximum [Member] | Cash and Money Market Funds [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Maximum [Member] | Common Equity Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	70.00%
Asset allocation of plan assets (in hundredths)	70.00%
Maximum [Member] | Common Equity Securities [Member] | Large cap [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	50.00%
Maximum [Member] | Common Equity Securities [Member] | Inflation hedge [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	10.00%
Maximum [Member] | Debt Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Weighted-average target asset allocations (in hundredths)	50.00%
Asset allocation of plan assets (in hundredths)	50.00%
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	21,096,000		17,518,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	21,096,000		17,518,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	21,096,000		17,518,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	21,096,000		17,518,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Money Market Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	534,000	[1]	498,000	[1]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	534,000	[1]	498,000	[1]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	534,000	[1]	498,000	[1]
Fair values of pension plan assets [Abstract]
Total Plan Assets	534,000	[1]	498,000	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common Equity Securities [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	3,974,000	[2]	3,755,000	[2]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	3,974,000	[2]	3,755,000	[2]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	3,974,000	[2]	3,755,000	[2]
Fair values of pension plan assets [Abstract]
Total Plan Assets	3,974,000	[2]	3,755,000	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	11,309,000	[3]	9,088,000	[3]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	11,309,000	[3]	9,088,000	[3]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	11,309,000	[3]	9,088,000	[3]
Fair values of pension plan assets [Abstract]
Total Plan Assets	11,309,000	[3]	9,088,000	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury Obligations [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0		0
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0		0
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0		0
Fair values of pension plan assets [Abstract]
Total Plan Assets	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Agencies [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0		0
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0		0
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0		0
Fair values of pension plan assets [Abstract]
Total Plan Assets	0		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate and Foreign Bonds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0	[4]	0	[4]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[4]	0	[4]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[4]	0	[4]
Fair values of pension plan assets [Abstract]
Total Plan Assets	0	[4]	0	[4]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed Income Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	5,279,000	[5]	4,177,000	[5]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	5,279,000	[5]	4,177,000	[5]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	5,279,000	[5]	4,177,000	[5]
Fair values of pension plan assets [Abstract]
Total Plan Assets	5,279,000	[5]	4,177,000	[5]
Significant Other Observable Inputs (Level 2) [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	1,570,000		2,297,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	1,570,000		2,297,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	1,570,000		2,297,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	1,570,000		2,297,000
Significant Other Observable Inputs (Level 2) [Member] | Cash and Money Market Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0	[1]	0	[1]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[1]	0	[1]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[1]	0	[1]
Fair values of pension plan assets [Abstract]
Total Plan Assets	0	[1]	0	[1]
Significant Other Observable Inputs (Level 2) [Member] | Common Equity Securities [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0	[2]	0	[2]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[2]	0	[2]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[2]	0	[2]
Fair values of pension plan assets [Abstract]
Total Plan Assets	0	[2]	0	[2]
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0	[3]	0	[3]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[3]	0	[3]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[3]	0	[3]
Fair values of pension plan assets [Abstract]
Total Plan Assets	0	[3]	0	[3]
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Obligations [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	355,000		593,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	355,000		593,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	355,000		593,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	355,000		593,000
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government Agencies [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	806,000		808,000
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	806,000		808,000
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	806,000		808,000
Fair values of pension plan assets [Abstract]
Total Plan Assets	806,000		808,000
Significant Other Observable Inputs (Level 2) [Member] | Corporate and Foreign Bonds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	409,000	[4]	896,000	[4]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	409,000	[4]	896,000	[4]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	409,000	[4]	896,000	[4]
Fair values of pension plan assets [Abstract]
Total Plan Assets	409,000	[4]	896,000	[4]
Significant Other Observable Inputs (Level 2) [Member] | Fixed Income Mutual Funds [Member]
Change in Plan Assets [Abstract]
Fair value of plan assets end of year	0	[5]	0	[5]
Accumulated benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[5]	0	[5]
Projected benefit obligation and fair value of plan assets [Abstract]
Fair value of plan assets	0	[5]	0	[5]
Fair values of pension plan assets [Abstract]
Total Plan Assets	$ 0	[5]	$ 0	[5]

[1] (a)The portfolios are designed to keep approximately three months of distributions in immediately available funds.

[2] (b)This category includes investments in U.S. common stocks widely distributed among consumer discretionary, consumer staples, healthcare, information technology, financial services, telecommunications, industrials, energy and utilities. The individual stocks are primarily large cap stocks which track with the S&P 500 with the exception of $339 (1.5% of total plan assets) which is invested in York Water Company common stock.

[3] (c)This category includes a majority of investments in closed-end mutual funds as well as domestic equity mutual funds, U.S. commodities used primarily as inflation hedges, and international mutual funds which give the portfolio exposure to small, mid and large cap index funds as well as international diversified index funds.

[4] (d)This category currently includes only U.S. corporate bonds and notes equitably distributed to the food and staples and information technology sectors.

[5] (e)This category includes fixed income investments in mutual funds which include municipal, government, corporate and mortgage securities of both the U.S. and other countries. The mortgage and asset-backed securities and non-U.S. corporate and sovereign investments add further diversity to the fixed income portion of the portfolio.