CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Interest-bearing deposits in banks and other financial institutions, collateral	$ 0	$ 1,000
Available-for-sale securities, amortized cost basis	1,519,643	1,224,227
Held-to-maturity securities, fair value	149,732	149,431
Allowance for loan and lease losses	$ 46,321	$ 39,539
Common stock, shares authorized (in shares)	65,000,000	65,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	56,941,493	56,926,978
Treasury stock, shares (in shares)	3,813,984	25,552,887