Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Net income	$ 4,551,000	$ 8,771,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	8,183,000	59,000
ESOP and stock compensation expense	894,000	1,764,000
Depreciation	795,000	771,000
Amortization of premiums, and deferred loan costs, net of (accretion) of discounts, and deferred loan fees	1,065,000	861,000
Amortization of intangible assets	55,000	69,000
Amortization of operating lease right-of-use assets	1,059,000	1,057,000
Income on bank owned life insurance	(876,000)	(896,000)
Losses (gains) on available-for-sale debt securities, net	13,000	(155,000)
Losses (gains) on trading securities, net	1,992,000	(1,086,000)
Net sales of trading securities	842,000	295,000
Decrease (increase) in accrued interest receivable	311,000	(246,000)
(Increase) decrease in other assets	(1,023,000)	3,118,000
Decrease in accrued expenses and other liabilities	(5,912,000)	(4,753,000)
Net cash provided by operating activities	11,949,000	9,629,000
Cash flows from investing activities:
Net increase in loans receivable	(72,609,000)	(11,156,000)
Purchases of Federal Home Loan Bank of New York stock	(7,515,000)	(1,125,000)
Redemptions of Federal Home Loan Bank of New York stock	17,235,000	1,125,000
Purchases of debt securities available-for-sale	(26,320,000)	(150,074,000)
Purchases of equity securities	(142,000)	(177,000)
Principal payments and maturities on debt securities available-for-sale	110,946,000	42,972,000
Principal payments and maturities on debt securities held-to-maturity	52,000	53,000
Proceeds from sale of debt securities available-for-sale	0	29,163,000
Proceeds from bank owned life insurance	2,000	0
Purchases and improvements of premises and equipment	(806,000)	(377,000)
Net cash provided by (used in) investing activities	20,843,000	(89,596,000)
Cash flows from financing activities:
Net increase in deposits	77,313,000	88,693,000
Dividends paid	(5,151,000)	(4,727,000)
Exercise of stock options	175,000	995,000
Increase in advance payments by borrowers for taxes and insurance	2,399,000	2,716,000
Repayments under capital lease obligations	0	(44,000)
Proceeds from securities sold under agreements to repurchase and other borrowings	220,353,000	25,397,000
Repayments related to securities sold under agreements to repurchase and other borrowings	(361,000,000)	(25,000,000)
Net cash (used in) provided by financing activities	(65,911,000)	88,030,000
Net (decrease) increase in cash and cash equivalents	(33,119,000)	8,063,000
Cash and cash equivalents at beginning of period	147,818,000	77,762,000
Cash and cash equivalents at end of period	114,699,000	85,825,000
Cash paid during the period for:
Interest	13,003,000	11,683,000
Income taxes	550,000	401,000
Non-cash transactions:
Loan charge-offs, net	90,000	70,000
Initial recognition of operating lease right-of use assets	0	43,560,000
Initial recognition of operating lease liabilities	$ 0	$ 47,328,000