Acquisitions - Additional Information (Detail) (USD $)	0 Months Ended		12 Months Ended	0 Months Ended
	Jul. 01, 2014	Jun. 17, 2014	Dec. 31, 2014 community Office	Jan. 27, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Total assets			$ 2,235,321,000		$ 2,191,559,000
Deposits			1,861,341,000		1,844,498,000
Assets under management, Carrying amount				3,000,000,000
Sterner Insurance Associates Inc [Member]
Business Acquisition [Line Items]
Acquisition completion date	Jul. 01, 2014
Cash paid for acquisition	3,900,000
Fair value of assumed liabilities with additional contingent consideration	940,000
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
Business Combination, Contingent Consideration, Cumulative Period	3 years
Goodwill related to acquisition, tax deductible	3,400,000
Customer-related intangibles	1,600,000
Amortization period	9 years
Valley Green Bank [Member]
Business Acquisition [Line Items]
Business merger, Date of merger agreement		Jun. 17, 2014
Total purchase price		78,900,000
Total assets			425,000,000
Loan			386,000,000
Deposits			385,000,000
Number of banking offices operated in greater Philadelphia marketplace (in offices)			3
Number of loan production offices in Philadelphia marketplace			2
Girard Partners [Member]
Business Acquisition [Line Items]
Acquisition completion date				Jan. 27, 2014
Cash paid for acquisition				5,400,000
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
Goodwill related to acquisition, tax deductible				6,800,000
Customer-related intangibles				4,300,000
Assets under management, Carrying amount				$ 500,000,000
Effective date of acquisition				Jan. 01, 2014
Customer related intangibles amortized period				9 years