CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 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	1,867,358	1,224,227
Held-to-maturity securities, fair value	138,262	149,431
Allowance for loan and lease losses	$ 47,671	$ 39,539
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	90,000,000	90,000,000
Common stock, issued (in shares)	57,411,821	56,926,978
Treasury stock, shares (in shares)	4,967,022	25,552,887