Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 21,862,000	$ 26,950,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred loan costs, fees and purchased premiums and discounts	656,000	1,102,000
Net amortization of premiums and discounts on securities	854,000	589,000
Net amortization of mortgage servicing rights	57,000	(52,000)
Amortization of intangible assets	514,000	0
Depreciation and amortization of office properties and equipment	3,314,000	2,170,000
Amortization of operating lease right-of-use assets	1,440,000	0
Provision for loan losses	15,304,000	548,000
Gain on securities transactions	(370,000)	(465,000)
Change in fair value of equity securities	(59,000)	(247,000)
Gain on sale of loans	(1,549,000)	(328,000)
Loss on real estate owned	0	1,000
Loss on disposal of office properties and equipment	691,000	0
Loss on write-down of mortgage servicing rights	34,000	0
Deferred tax expense (benefit)	7,220,000	(7,160,000)
(Increase) in accrued interest receivable	(5,643,000)	(1,416,000)
(Increase) in other assets	(80,652,000)	(34,322,000)
Increase in accrued expenses and other liabilities	36,507,000	12,880,000
Income on bank-owned life insurance	(2,936,000)	(2,665,000)
Employee stock ownership plan expense	1,695,000	1,738,000
Stock based compensation	4,409,000	0
Increase in deferred compensation obligations under Rabbi Trust	(176,000)	(98,000)
Net cash provided by operating activities	3,172,000	(775,000)
Cash flows from investing activities:
Proceeds from sales of debt securities available for sale	20,761,000	15,711,000
Proceeds from sales of equity securities	0	765,000
Proceeds from paydowns/maturities/calls of debt securities available for sale	94,758,000	49,569,000
Proceeds from paydowns/maturities/calls of debt securities held to maturity	24,971,000	9,964,000
Purchases of debt securities available for sale	(111,113,000)	(80,499,000)
Purchases of debt securities held to maturity	0	(47,671,000)
Purchases of equity securities	0	(417,000)
Proceeds from sales of loans held-for-sale	103,992,000	45,003,000
Proceeds from sales of loans receivable	22,876,000	2,483,000
Purchases of loans receivable	0	(29,885,000)
Net increase in loans receivable	(409,327,000)	(168,486,000)
Proceeds from redemptions of Federal Home Loan Bank stock	35,660,000	32,851,000
Purchases of Federal Home Loan Bank stock	(21,914,000)	(32,526,000)
Additions to office properties and equipment	(2,852,000)	(11,387,000)
Proceeds from sale of real estate owned	0	91,000
Net cash acquired in acquisition	155,248,000	0
Net cash used in investing activities	(86,940,000)	(214,434,000)
Cash flows from financing activities:
Net increase in deposits	602,033,000	254,772,000
Proceeds from long-term borrowings	90,000,000	78,991,000
Payments on long-term borrowings	(116,465,000)	(160,000,000)
Net (decrease) increase in short-term borrowings	(288,306,000)	55,100,000
Increase in advance payments by borrowers for taxes and insurance	217,000	2,389,000
Purchase of treasury stock	(53,361,000)	(3,867,000)
Restricted stock forfeitures	(16,000)	0
Net cash provided by financing activities	234,102,000	227,385,000
Net increase in cash and cash equivalents	150,334,000	12,176,000
Cash and cash equivalents at beginning of year	75,547,000	42,201,000
Cash and cash equivalents at end of period	225,881,000	54,377,000
Cash paid during the period for:
Interest on deposits and borrowings	43,801,000	21,491,000
Income tax payments, net of (refunds)	1,300,000	(5,174,000)
Non-cash investing and financing activities:
Transfer of loans receivable to loans held-for-sale	112,219,000	38,966,000
Securitization of loans	0	21,615,000
Initial recognition of operating lease right-of-use assets	22,218,000	0
Initial recognition of operating lease liabilities	23,290,000	0
Non-cash assets acquired:
Debt securities available for sale	51,479,000	0
Debt securities held to maturity	13,418,000	0
Equity securities	1,796,000	0
Federal Home Loan Bank stock	2,010,000	0
Loans receivable	171,593,000	0
Accrued interest receivable	679,000	0
Office properties and equipment, net	5,774,000	0
Bank-owned life insurance	17,245,000	0
Other assets	2,823,000	0
Total non-cash assets acquired	266,817,000	0
Liabilities assumed:
Deposits	333,234,000	0
Borrowings	37,728,000	0
Advance payments by borrowers for taxes and insurance	982,000	0
Accrued expenses and other liabilities	5,400,000	0
Total liabilities assumed	377,344,000	0
Net non-cash liabilities acquired	(110,527,000)	0
Net cash and cash equivalents acquired in acquisition	$ 155,248,000	$ 0