Condensed Financial Information - Parent Company Only - Schedule of Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Jul. 01, 2016	Dec. 31, 2015	Jan. 01, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Cash and due from banks	$ 48,757		$ 32,356		$ 31,995	$ 32,646
Investments in subsidiaries, at equity in net assets:
Other assets	20		0
Total assets	4,230,528		2,879,451
Liabilities:
Subordinated notes	94,087		49,377
Other liabilities	49,972		49,929
Total liabilities	3,725,319		2,517,877
Shareholders' equity:	505,209		361,574		284,554	280,506
Total liabilities and shareholders’ equity	4,230,528		2,879,451
Common Stock Issued - acquisition, Value	144,559		110,271
Parent Company [Member]
Assets:
Cash and due from banks	1,980		17,096		$ 3,120	$ 2,999
Investments in securities	914		807
Investments in subsidiaries, at equity in net assets:
Bank	587,532		392,304
Non-banks	0		0
Other assets	32,124		24,950
Total assets	622,550		435,157
Liabilities:
Dividends payable	5,316		3,905
Subordinated notes	94,087		49,377
Other liabilities	17,938		20,301
Total liabilities	117,341		73,583
Shareholders' equity:	505,209		361,574
Total liabilities and shareholders’ equity	$ 622,550		$ 435,157
Fox Chase Bank [Member]
Investments in subsidiaries, at equity in net assets:
Total assets		$ 1,100,000
Fox Chase Bank [Member] | Parent Company [Member]
Liabilities:
Common Stock Issued - acquisition, Value		$ 227,000
Valley Green Bank [Member] | Parent Company [Member]
Liabilities:
Common Stock Issued - acquisition, Value				$ 77,000