Retirement Plans (Details Textual)	6 Months Ended
	Jun. 30, 2012 Age
SERP [Member]
Retirement Plans (Textual) [Abstract]
Defined Benefit Plan description	The Company maintains a Supplemental Executive Benefit Plan (SERP) in order to provide supplemental retirement and death benefits for certain key employees of the Company. Under the SERP, participants shall receive an annual retirement benefit following retirement at age 65 equal to 25% of the participant’s final average pay multiplied by a ratio, ranging from 1.25% to 25.0%, based on the participant’s total years of service. Final average pay is based upon the participant’s last three year’s compensation. The maximum ratio of 25% requires twenty or more years of credited service and the minimum ratio of 1.25% requires one year of credited service. Benefits under the plan are payable in either a lump sum or ten equal annual payments and a lesser benefit is payable upon early retirement at age 50 with at least twelve years of service. If a participant dies prior to retirement, the participant’s estate will receive a lump sum payment equal to the net present value of future benefit payments under the plan. At June 30, 2012,, the participants in the plan had credited service under the SERP ranging from 21 to 33 years.
Annual retirement age	65
Annual retirement benefit	25.00%
Final average pay	3 years
Credited service description	twenty or more years
Credited service	1 year
Number of payments	sum or ten equal annual payments
Early retirement age	50
Early retirement age, period	12 years
SERP [Member] | Maximum [Member]
Retirement Plans (Textual) [Abstract]
Final average pay multiplied by a ratio	25.00%
Net present value of future benefit payments	33 years
SERP [Member] | Minimum [Member]
Retirement Plans (Textual) [Abstract]
Final average pay multiplied by a ratio	1.25%
Net present value of future benefit payments	21 years
Directors' Retirement Plan [Member]
Retirement Plans (Textual) [Abstract]
Defined Benefit Plan description	The Company and the Bank maintain the ESB Financial Corporation Directors’ Retirement Plan and have entered into director retirement agreements with each director of the Company and the Bank. The plan provides that any retiring director with a minimum of five or more years of service with the Company or the Bank and a minimum of 10 total years of service, including years of service with any bank acquired by the Company or the Bank, that remains in continuous service as a board member until age 75 will be entitled to receive an annual retirement benefit equal to his or her director’s fees earned during the last full calendar year prior to his or her retirement date, multiplied by a ratio, ranging from 25% to 80%, based on the director’s total years of service. The maximum ratio of 80% of fees requires 20 or more years of service and the minimum ratio of 25% of fees requires 10 years of service. Retirement benefits may also be payable under the plan if a director retires from service as a director prior to attaining age 75. Three directors are currently receiving monthly benefits under the plan.
Retirement Plan and have entered into director retirement agreements	five or more years
Service required for Maximum ratio of 80% of fees	20 or more years of service
Service required for Minimum ratio of 25% of fees	10 years
Directors retirement age	75
Number of directors receiving benefits	3
Directors' Retirement Plan [Member] | Maximum [Member]
Retirement Plans (Textual) [Abstract]
Final average pay multiplied by a ratio	80.00%
Directors' Retirement Plan [Member] | Minimum [Member]
Retirement Plans (Textual) [Abstract]
Final average pay multiplied by a ratio	25.00%
Retirement Plan and have entered into director retirement agreements, periods	10 years