Consolidated Statements of Cash Flows - USD ($)		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income		$ 36,086,000	$ 86,173,000	$ 92,049,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred loan costs, fees and purchased premiums and discounts		5,606,000	6,063,000	2,121,000
Net amortization of premiums and discounts on securities		1,440,000	2,771,000	4,482,000
Net amortization of mortgage servicing rights		239,000	233,000	266,000
Amortization of intangible assets		2,350,000	1,980,000	1,025,000
Depreciation and amortization of office properties and equipment		7,767,000	7,317,000	6,718,000
Amortization of operating lease right-of-use assets		3,916,000	3,821,000	3,633,000
Loss on extinguishment of debt		300,000	0	2,851,000
Provision for (reversal of) credit losses	[1]	4,787,000	5,485,000	(9,953,000)
Net loss (gain) on securities transactions		10,847,000	(210,000)	(2,025,000)
Change in fair value of equity securities		(695,000)	401,000	1,792,000
Gain on securitizations		0	0	(2,259,000)
Gain on sale of loans, net		(1,214,000)	(178,000)	(8,531,000)
Net loss on disposal of office properties and equipment		168,000	242,000	95,000
Deferred tax (benefit) expense		3,375,000	12,769,000	17,709,000
(Increase) decrease in accrued interest receivable		(5,447,000)	(4,689,000)	2,023,000
(Increase) in other assets		(33,992,000)	(9,884,000)	(22,159,000)
Increase in accrued expenses and other liabilities		3,282,000	24,998,000	1,926,000
Income on bank-owned life insurance		(10,126,000)	(7,393,000)	(5,994,000)
Employee stock ownership plan expense		4,095,000	4,850,000	4,052,000
Stock based compensation		7,979,000	7,440,000	8,880,000
(Decrease) increase in deferred compensation obligations under Rabbi Trust		(47,000)	(31,000)	3,000
Net cash provided by operating activities		40,716,000	142,158,000	98,704,000
Cash flows from investing activities:
Proceeds from sales of debt securities available for sale		277,022,000	126,772,000	90,339,000
Proceeds from sales of equity securities		0	0	1,390,000
Proceeds from paydown/maturities/calls of debt securities available for sale		100,855,000	281,959,000	368,249,000
Proceeds from paydown/maturities/calls of debt securities held to maturity		20,221,000	31,151,000	36,103,000
Purchases of debt securities available for sale		(124,618,000)	(147,181,000)	(667,015,000)
Purchases of debt securities held to maturity		0	(23,298,000)	(203,779,000)
Purchases of equity securities		0	0	(91,000)
Proceeds from sales of loans held-for-sale		121,372,000	9,639,000	302,039,000
Purchases of loans receivable		(14,729,000)	(8,315,000)	(85,382,000)
Net increase in loans receivable		(311,299,000)	(987,753,000)	(325,917,000)
Proceeds from bank-owned life insurance death benefits		1,364,000	1,031,000	5,000
Proceeds from redemptions of Federal Home Loan Bank stock		91,132,000	77,362,000	28,448,000
Purchases of Federal Home Loan Bank stock		(114,040,000)	(111,429,000)	(4,798,000)
Proceeds from sales of office properties and equipment		0	1,772,000	1,879,000
Additions to office properties and equipment		(7,635,000)	(7,204,000)	(5,492,000)
Net cash acquired in acquisitions		0	140,769,000	20,417,000
Net cash provided by (used in) investing activities		39,645,000	(614,725,000)	(443,605,000)
Cash flows from financing activities:
Net (decrease) increase in deposits		(154,603,000)	(71,789,000)	581,475,000
Proceeds from long-term borrowings		536,113,000	335,893,000	37,120,000
Payments on long-term borrowings		(11,300,000)	(38,725,000)	(306,752,000)
Net (decrease) increase in short-term borrowings		(93,165,000)	446,808,000	(244,027,000)
Proceeds from term note		0	0	29,841,000
Repayment of term note		(30,300,000)	0	0
(Decrease) increase in advance payments by borrowers for taxes and insurance		(1,951,000)	7,648,000	3,406,000
Issuance of common stock for restricted stock awards		10,000	0	0
Purchase of treasury stock		(80,497,000)	(93,996,000)	(107,774,000)
Exercise of stock options		(24,000)	(393,000)	(25,000)
Repurchase of shares for taxes		(623,000)	(4,614,000)	(357,000)
Net cash provided by (used in) financing activities		163,660,000	580,832,000	(7,093,000)
Net increase (decrease) in cash and cash equivalents		244,021,000	108,265,000	(351,994,000)
Cash and cash equivalents at beginning of year		179,228,000	70,963,000	422,957,000
Cash and cash equivalents at end of year		423,249,000	179,228,000	70,963,000
Cash paid during the period for:
Interest on deposits and borrowings		183,568,000	41,077,000	37,906,000
Income tax payments, net of refunds		9,253,000	15,729,000	16,262,000
Non-cash investing and financing activities:
Transfer of loans receivable to loans held-for-sale		120,955,000	9,461,000	289,362,000
Securitization of loans		0	0	99,603,000
Excise tax on net stock repurchases		800,000	0	0
Non-cash assets acquired:
Debt securities available for sale		0	79,024,000	118,017,000
Equity securities		0	1,075,000	0
Federal Home Loan Bank stock		0	906,000	3,032,000
Loans receivable		0	335,501,000	158,912,000
Accrued interest receivable		0	910,000	867,000
Office properties and equipment, net		0	7,296,000	5,934,000
Bank-owned life insurance		0	13,033,000	8,661,000
Core deposit intangibles		0	9,780,000	42,000
Other assets		0	6,356,000	616,000
Total non-cash assets acquired		0	453,881,000	296,081,000
Liabilities assumed:
Deposits		0	502,732,000	210,117,000
Borrowings		0	5,762,000	59,908,000
Advance payments by borrowers for taxes and insurance		0	1,341,000	495,000
Accrued expenses and other liabilities		0	10,568,000	4,822,000
Total liabilities assumed		0	520,403,000	275,342,000
Net non-cash (liabilities assumed) assets acquired		0	(66,522,000)	20,739,000
Net cash and cash equivalents acquired in acquisitions		$ 0	$ 140,769,000	$ 20,417,000

[1] (1) The Company adopted ASU 2016-13 as of January 1, 2022. Prior year period has not been restated.