Acquisition - Supplemental Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings per share
Restructuring charges	$ 1,731	$ 1,642	$ 0
Fox Chase Bank [Member]
Business Acquisition [Line Items]
Net interest income	132,581	130,452
Noninterest income	58,189	55,158
Noninterest expense	168,170	132,600
Net income	$ 11,933	$ 38,767
Earnings per share
Basic (in dollars per share)	$ 0.45	$ 1.46
Diluted (in dollars per share)	$ 0.45	$ 1.46
Acquisition and integration costs	$ (29,433)	$ (3,028)
Acquisition and integration costs, net of tax	$ (19,939)	$ (2,156)
Basic (in dollars per share)	$ (0.76)	$ (0.08)
Diluted (in dollars per share)	$ (0.76)	$ (0.08)
Restructuring charges	$ (1,731)	$ (1,642)
Restructuring charges, net of tax	$ (1,125)	$ (1,067)
Basic (in dollars per share)	$ (0.04)	$ (0.04)
Diluted (in dollars per share)	$ (0.04)	$ (0.04)