Fair Value Disclosures - Additional Information (Detail) (USD $)	12 Months Ended			0 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 01, 2014	Jan. 27, 2014	May 01, 2013	Jun. 30, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation adjustments for loans held for sale	$ 0	$ 0
Carrying value of impaired loans held for investment	56,191,000	58,333,000
Valuation allowance of impaired loans held for investment	998,000	2,963,000
Mortgage Servicing Rights Carrying Amount Before Valuation Allowance	5,500,000	5,800,000
Mortgage Servicing Rights Valuation Allowance	0	250,000
Goodwill impairment	0	0	0
Impairment of intangible assets	0
Fair Value Measured on Recurring Basis [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	315,071,000	336,627,000
Level 3 [Member] | Fair Value Measured on Recurring Basis [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
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				5,700,000
Potential cash payments from contingent consideration, period of measurement (in years)				3 years
Potential cash payments from contingent consideration, end date				Jun. 30, 2017
Fair value of contingent consideration liability				635,000
Original potential cash payments from contingent consideration, minimum				0
Original potential cash payments from contingent consideration, maximum				5,700,000
Girard Partners [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					14,500,000
Potential cash payments from contingent consideration, period of measurement (in years)					5 years
Potential cash payments from contingent consideration, end date					Dec. 31, 2018
Fair value of contingent consideration liability					5,500,000
Original potential cash payments from contingent consideration, minimum					0
Original potential cash payments from contingent consideration, maximum					14,500,000
John T Fretz Insurance Agency [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						620,000
Potential cash payments from contingent consideration, end date						Apr. 30, 2016
Remaining potential cash payments from contingent consideration, period of measurement (in years)						2 years
Javers Group [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Potential cash payments from contingent consideration, period of measurement (in years)							3 years
Potential cash payments from contingent consideration, end date							Jun. 30, 2015
Reduction of other noninterest expense							959,000
Fair value of contingent consideration liability	0
Original potential cash payments from contingent consideration, minimum							0
Original potential cash payments from contingent consideration, maximum							$ 1,700,000