Aggregate number of common shares reserved for future issuance.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

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-Section S99

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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Weighted average purchase price of capital shares purchased through an employee stock ownership plan.

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The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares of capital stock issued (purchased by employees) in connection with an employee stock ownership plan.

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-Name Regulation S-X (SX)

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The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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SHARE-BASED COMPENSATION PLANS - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Aug. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	May. 31, 2011
Orrstown 2011 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved to be issued							381,920
Shares to be issued under employee stock purchase plan		160,227		160,227
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved to be issued		350,000		350,000
Shares to be issued under employee stock purchase plan		192,338		192,338
Maximum shares purchase, as percentage of salary		10.00%		10.00%
Percentage of value of the shares on the semi-annual offering	85.00%			95.00%
Shares purchased by employees		3,341	3,668	6,305	6,707
Weighted average price (in usd per share)		$ 15.91	$ 15.56	$ 15.83	$ 14.88
Compensation expense recognized		$ 5	$ 4	$ 8	$ 12
Restricted Stock \| Orrstown 2011 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense on Restricted stock awards		229	58	525	67
Tax benefits from compensation expense		80	$ 20	184	$ 23
Unrecognized compensation expense		$ 2,508		$ 2,508		$ 2,094
Unrecognized compensation expense, recognition period				3 years 6 months
Employee Stock Option \| Orrstown 2011 Incentive Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term to exercise option				10 years