Investment securities - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014 Security	Dec. 31, 2013 Security	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Unrealized gains, net	$ 4,090,000	$ 1,826,000
Net of deferred income taxes	2,202,000	984,000
Proceeds from the sale of investment securities available-for-sale	15,389,000	4,573,000	5,821,000
Gross realized gains	919,000	163,000	317,000
Gross realized losses	58,000	0	0
Income tax provision applicable to net realized gains	301,000	55,000	108,000
Carrying value of securities pledged	216,192,000	202,407,000
Number of investment securities held	52pfis_NumberOfInvestmentSecuritiesOwned	153pfis_NumberOfInvestmentSecuritiesOwned
State and Municipals, Tax-Exempt [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities held	16	79
Number of securities in continuous unrealized loss positions 12 months or longer	4
State and Municipals, Taxable [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities held	1	16
Number of securities in continuous unrealized loss positions 12 months or longer	1
U.S. Government-Sponsored Enterprises State and Municipals [Member]
Schedule of Available-for-sale Securities [Line Items]
Maximum percentage of stockholders' equity exceeded for securities of any individual issuer	10.00%	10.00%
Number of investment securities held	9	39
Number of securities in continuous unrealized loss positions 12 months or longer	2	1
Other-than-temporary impairments recognized	$ 0	$ 0	$ 0
Mortgage-backed Securities, Issued by Government Agencies [Member] \| United States [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities held	26	16
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities held		1
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of investment securities held		2

Available For Sale Securities, Income Tax Benefit On Realized Gains Losses

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Available For Sale Securities Unrealized Gain Loss Net Of Tax

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Deferred Tax Liabilities Unrealized Gains On Available For Sale Securities

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Maximum Percentage Of Stockholders Equity Exceeded For Securities Of Any Individual Issuer

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Number Of Investment Securities Owned

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Number Of Securities In Continuous Unrealized Loss Position 12 Months Or Longer

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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The fair value of available-for-sale securities that serve as collateral for borrowings.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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