Parent Company financial statements - Condensed Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 17,649us-gaap_NetIncomeLoss	$ 5,721us-gaap_NetIncomeLoss	$ 10,589us-gaap_NetIncomeLoss
Adjustments:
Decrease (increase) in other assets	(5,978)	875	(449)
Increase (decrease) in other liabilities	2,074	1,048	123
Stock based compensation	70us-gaap_ShareBasedCompensation	25us-gaap_ShareBasedCompensation	40us-gaap_ShareBasedCompensation
Deferred income tax expense	1,146us-gaap_DeferredIncomeTaxExpenseBenefit	(1,143)us-gaap_DeferredIncomeTaxExpenseBenefit	353us-gaap_DeferredIncomeTaxExpenseBenefit
Net cash provided by operating activities	20,562	9,705	11,546
Cash flows from investing activities:
Proceeds from sale of available-for-sale securities	15,389	4,573	5,821
Purchase of available-for-sale securities	(102,304)	(15,262)	(46,297)
Net cash provided by (used in) investing activities	71,909	14,807	20,717
Cash flows from financing activities:
Redemption of common stock	(109)pfis_PaymentsForRedemptionOfCommonStock
Retirement of stock options	(83)pfis_PaymentForSettlementOfStockOptions
Reissuance of treasury stock	21
Purchase of treasury stock	(70)
Cash dividends paid	(9,360)us-gaap_PaymentsOfDividends	(5,511)us-gaap_PaymentsOfDividends	(5,504)us-gaap_PaymentsOfDividends
Net cash provided by (used in) financing activities	31,463	8,568	(18,899)
Net increase (decrease) in cash and cash equivalents	(19,884)	3,466	13,364
Cash and cash equivalents at beginning of year	51,310	47,844	34,480
Cash and cash equivalents at end of year	31,426	51,310	47,844
Peoples Bank [Member]
Cash flows from operating activities:
Net income	17,649	5,721	10,589
Adjustments:
Net realized gains on sales of securities	(375)	(103)	(136)
Undistributed net income of subsidiaries	(8,110)	2,689	(5,038)
Decrease (increase) in other assets	1,182	(1,733)
Increase (decrease) in other liabilities	(511)	641	(28)
Stock based compensation	70	25	40
Deferred income tax expense		1	36
Increase in due from subsidiaries		(1,611)
Net cash provided by operating activities	9,905	5,630	5,463
Cash flows from investing activities:
Proceeds from sale of available-for-sale securities	722	253	145
Purchase of available-for-sale securities			(103)
Net cash provided by (used in) investing activities	722	253	42
Cash flows from financing activities:
Redemption of common stock	(109)
Retirement of stock options	(83)
Reissuance of treasury stock	21
Purchase of treasury stock	(70)
Cash dividends paid	(9,360)	(5,511)	(5,504)
Net cash provided by (used in) financing activities	(9,601)	(5,511)	(5,504)
Net increase (decrease) in cash and cash equivalents	1,026	372	1
Cash and cash equivalents at beginning of year	3,157	2,785	2,784
Cash and cash equivalents at end of year	$ 4,183	$ 3,157	$ 2,785

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