Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Investment securities held to maturity, fair value	$ 87,561	$ 112,830
Premises and equipment, accumulated depreciation and amortization	76,763	70,140
Identified intangible assets, accumulated amortization	$ 37,481	$ 35,818
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	85,177,172	85,177,172
Treasury stock, shares	5,003,127	5,020,025
Unallocated common stock held by ESOP, shares	79,548	109,950