Fair Value Measurements - Book Value and Estimated Fair Value of Bank's Significant Financial Instruments Not Recorded at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial Assets:
Securities held-to-maturity	$ 378,613	$ 397,763
Financial Liabilities:
Time deposits	267,420	255,423
Securities sold under agreements to repurchase with retail customers	83,913	75,872
Book Value [Member]
Financial Assets:
Cash and due from banks	34,261	43,946
Securities held-to-maturity	375,616	394,813
Federal Home Loan Bank of New York stock	16,645	19,978
Loans receivable, net and mortgage loans held for sale	2,000,379	1,973,400
Financial Liabilities:
Deposits other than time deposits	1,703,940	1,661,255
Time deposits	267,420	255,423
Securities sold under agreements to repurchase with retail customers	83,913	75,872
Federal Home Loan Bank advances and other borrowings	274,417	346,885
Level 1 Inputs [Member]
Financial Assets:
Cash and due from banks	34,261	43,946
Financial Liabilities:
Securities sold under agreements to repurchase with retail customers	83,913	75,872
Level 2 Inputs [Member]
Financial Assets:
Securities held-to-maturity	378,613	397,763
Financial Liabilities:
Deposits other than time deposits	1,703,940	1,661,255
Time deposits	269,034	255,564
Federal Home Loan Bank advances and other borrowings	276,905	346,118
Level 3 Inputs [Member]
Financial Assets:
Federal Home Loan Bank of New York stock	16,645	19,978
Loans receivable, net and mortgage loans held for sale	$ 2,030,537	$ 1,986,891