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, 2017	Dec. 31, 2016
Financial Assets:
Securities held-to-maturity	$ 695,564	$ 598,119
Federal Home Loan Bank of New York stock, at cost	19,253	19,313
Financial Liabilities:
Time deposits		647,103
Securities sold under agreements to repurchase with retail customers	77,207	69,935
Book Value
Financial Assets:
Cash and due from banks	175,252	301,373
Securities held-to-maturity	695,918	598,691
Federal Home Loan Bank of New York stock, at cost	19,253	19,313
Loans receivable, net and mortgage loans held for sale	3,825,883	3,804,994
Federal Home Loan Bank advances and other borrowings	306,612	307,057
Financial Liabilities:
Deposits other than time deposits	3,566,263	3,540,647
Time deposits	632,400	647,103
Securities sold under agreements to repurchase with retail customers		69,935
Level 1 Inputs
Financial Assets:
Cash and due from banks	175,252	301,373
Securities held-to-maturity	8,588	8,550
Financial Liabilities:
Securities sold under agreements to repurchase with retail customers	77,207	69,935
Level 2 Inputs
Financial Assets:
Securities held-to-maturity	684,320	586,504
Federal Home Loan Bank advances and other borrowings	304,646	304,901
Financial Liabilities:
Deposits other than time deposits	3,566,263	3,540,647
Time deposits	628,870	644,354
Level 3 Inputs
Financial Assets:
Securities held-to-maturity	2,656	3,030
Federal Home Loan Bank of New York stock	19,253	19,313
Loans receivable, net and mortgage loans held for sale	$ 3,858,364	$ 3,834,677