Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Securities held-to-maturity, net estimated fair value	$ 864,173,000	$ 761,660,000
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference	$ 1,000,000	$ 1,000,000
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	48,382,370	48,382,370
Common stock, shares outstanding	48,382,370	32,596,893
Treasury stock, shares	0	969,879