Fair Value Measurements - Book Value and Estimated Fair Value of Bank's Significant Financial Instruments Not Recorded at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financial Assets:
Securities held-to-maturity	$ 397,763	$ 474,215
Financial Liabilities:
Time deposits	255,423	207,218
Securities sold under agreements to repurchase with retail customers	75,872	67,812
Book Value [Member]
Financial Assets:
Cash and due from banks	43,946	36,117
Securities held-to-maturity	394,813	469,417
Federal Home Loan Bank of New York stock	19,978	19,170
Loans receivable and mortgage loans held-for-sale	1,973,400	1,693,047
Financial Liabilities:
Deposits other than time deposits	1,661,255	1,512,917
Time deposits	255,423	207,218
Securities sold under agreements to repurchase with retail customers	75,872	67,812
Federal Home Loan Bank advances and other borrowings	346,885	332,738
Level 1 Inputs [Member]
Financial Assets:
Cash and due from banks	43,946	36,117
Financial Liabilities:
Securities sold under agreements to repurchase with retail customers	75,872	67,812
Level 2 Inputs [Member]
Financial Assets:
Securities held-to-maturity	397,763	474,215
Financial Liabilities:
Deposits other than time deposits	1,661,255	1,512,917
Time deposits	255,564	208,651
Federal Home Loan Bank advances and other borrowings	346,118	332,432
Level 3 Inputs [Member]
Financial Assets:
Federal Home Loan Bank of New York stock	19,978	19,170
Loans receivable and mortgage loans held-for-sale	$ 1,986,891	$ 1,709,819