Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)		12 Months Ended
	Jul. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill And Other Intangible Assets [Line Items]
Amortization of Intangible Assets		$ 4,100,000	$ 3,600,000	$ 3,300,000
Goodwill		172,559,000	112,657,000	67,717,000
Additional goodwill		59,902,000	44,940,000
Goodwill impairment		0	0	0
Material impairments to identifiable intangible assets		0	0	0
Aggregate fair value of mortgage servicing rights		$ 9,500,000	$ 8,000,000
Range of discount rates used for valuation of mortgage servicing rights		10.00%	10.00%
Fox Chase Bank [Member]
Goodwill And Other Intangible Assets [Line Items]
Additional goodwill	$ 59,900,000
Customer Related Intangibles [Member]
Goodwill And Other Intangible Assets [Line Items]
Impairment on customer related intangibles		$ 0	$ 0	$ 31,000
Core Deposits [Member] | Fox Chase Bank [Member]
Goodwill And Other Intangible Assets [Line Items]
Core deposit intangibles	$ 5,300,000