Unaudited Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Investment securities held-to-maturity, fair value	$ 78,079	$ 93,695
Premises and equipment, accumulated depreciation and amortization	57,032	51,722
Identified intangible assets, accumulated amortization	$ 31,028	$ 29,149
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	75,744,445	75,744,445
Treasury stock, shares (in shares)	4,734,512	4,861,554
Unallocated common stock held by ESOP, shares (in shares)	185,787	213,066