Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 40,079	$ 24,768	$ 26,130
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,615	1,411	635
ESOP and stock compensation expense	7,769	8,686	9,555
Depreciation expense	3,020	3,229	3,591
Amortization of premiums, and deferred loan costs, net of (accretion) of discounts, and deferred loan fees	2,441	2,000	2,226
Amortization of intangible assets	326	386	447
Income on bank owned life insurance	(3,705)	(5,386)	(3,998)
Proceeds from sale of loans held-for-sale	0	494	0
Losses (gains) on securities, net	701	(1,283)	(813)
Net purchases of trading securities	(250)	(626)	(637)
(Increase) decrease in accrued interest receivable	(2,246)	(999)	1
Decrease (increase) in other assets	3,563	(3,689)	3,052
Deferred taxes	(893)	15,193	(3,059)
(Decrease) increase in accrued expenses and other liabilities	(631)	(560)	571
Net cash provided by (used in) operating activities	52,789	43,624	37,701
Cash flows from investing activities:
Net increase in loans receivable	(69,270)	(110,177)	(87,514)
Purchase of loans	(37,593)	(64,116)	(167,345)
Purchase of FHLB of New York stock	(21,557)	(18,890)	(9,497)
Redemption of FHLB of New York stock	24,086	18,967	10,653
Purchases of debt securities available-for-sale	(451,174)	(137,631)	(105,860)
Principal payments and maturities on debt securities available-for-sale	118,485	114,416	162,594
Principal payments and maturities on debt securities held-to-maturity	403	200	181
Proceeds from sale of debt securities available-for-sale	32,115	4,975	44,582
Proceeds from sale of equity securities	0	966	0
Proceeds from bank owned life insurance	174	2,829	0
Proceeds from sale of other real estate owned	850	0	45
Purchases and improvements of premises and equipment	(2,879)	(2,065)	(932)
Net cash acquired in business combinations	0	0	55,479
Net cash provided by investing activities	(406,360)	(190,526)	(97,614)
Cash flows from financing activities:
Net increase in deposits	449,533	123,392	204,455
Dividends paid	(18,673)	(15,646)	(14,074)
Exercise of stock options	2,088	100	120
Purchase of treasury stock	(5)	0	(2,201)
Additional tax benefit on equity awards	0	0	1,512
Increase in advance payments by borrowers for taxes and insurance	3,209	2,467	1,469
Repayments under capital lease obligations	(255)	(224)	(204)
Proceeds from securities sold under agreements to repurchase and other borrowings	397,312	441,570	228,978
Repayments related to securities sold under agreements to repurchase and other borrowings	(459,715)	(443,003)	(315,910)
Net cash used in financing activities	373,494	108,656	104,145
Net (decrease) increase in cash and cash equivalents	19,923	(38,246)	44,232
Cash and cash equivalents at beginning of period	57,839	96,085	51,853
Cash and cash equivalents at end of period	77,762	57,839	96,085
Supplemental cash flow information:
Interest	35,822	23,765	22,037
Income taxes	10,368	12,875	14,415
Non-cash transactions:
Loans charged-off / (recoveries), net	1,278	(154)	810
Transfers of loans to other real estate owned	0	0	850
Transfers of originated loans held-for-investment to held-for-sale, at fair value	0	494	0
Securities available-for-sale	0	0	61,633
Loans	0	0	342,566
Accrued interest receivable	0	0	1,452
Bank owned life insurance	0	0	11,269
Premises and equipment	0	0	5,926
Federal Home Loan Bank of New York stock	0	0	476
Goodwill and other intangible assets	0	0	24,265
Other assets	0	0	5,389
Total non-cash assets acquired	0	0	452,976
Deposits	0	0	456,203
Borrowings	0	0	2,213
Other liabilities	0	0	8,318
Total non-cash liabilities assumed	0	0	466,734
Net non-cash assets acquired	0	0	(13,758)
Net cash and cash equivalents acquired	0	0	55,479
Common stock issued in acquisition	$ 0	$ 0	$ 41,721