Fair Value Disclosures - Additional Information (Detail)		3 Months Ended		12 Months Ended
	Jul. 01, 2014 USD ($)	Dec. 31, 2016 USD ($) loan	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) loan property	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent Consideration from New Acquisition				$ 0	$ 1,525,000	$ 6,105,000
Adjustment of Contingent Consideration				2,974,000	142,000
Valuation adjustments for loans held for sale				0	0
Carrying value of impaired loans held for investment		$ 43,915,000		43,915,000
Valuation allowance of impaired loans held for investment		235,000		235,000	322,000
Mortgage Servicing Rights Carrying Amount Before Valuation Allowance		6,500,000		6,500,000	5,900,000
Mortgage Servicing Rights Valuation Allowance		0		0	0
Goodwill impairment				0	0	$ 0
Impairment of intangible assets				$ 0
Number of properties written-down | property				4
OREO write-downs				$ 469,000
Sterner Insurance Associates Inc [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Potential cash payments from contingent consideration, minimum	$ 0
Potential cash payments from contingent consideration, maximum	$ 2,600,000
Potential cash payments from contingent consideration, period of measurement (in years)	12 months
Potential cash payments from contingent consideration, end date	2017
Contingent Consideration from New Acquisition			$ 1,500,000	0	1,525,000
Adjustment of Contingent Consideration				512,000	690,000
Girard Partners [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent Consideration from New Acquisition				0	0
Adjustment of Contingent Consideration		5,300,000		2,394,000	(642,000)
Reduction of other noninterest expense				2,100,000	550,000
John T Fretz Insurance Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent Consideration from New Acquisition				0	0
Adjustment of Contingent Consideration				68,000	94,000
Held for Investment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value of impaired loans held for investment		43,900,000		43,900,000	48,933,000
Valuation allowance of impaired loans held for investment		$ 235,000		$ 235,000	$ 322,000
Derivative Financial Instruments, Liabilities [Member] | Interest Rate Swap [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of Loans with Unrealized Gain | loan		2		2
Unrealized Gain On Loans		$ 97,000		$ 97,000