Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income	$ 92,049,000	$ 57,603,000	$ 54,717,000
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred loan fees, costs, and purchased premiums and discounts	2,121,000	(1,464,000)	1,205,000
Net amortization of premiums and discounts on securities	4,482,000	2,508,000	1,160,000
Net amortization of mortgage servicing rights	266,000	130,000	(109,000)
Amortization of intangible assets	1,025,000	1,048,000	222,000
Depreciation and amortization of office properties and equipment	6,718,000	6,543,000	4,880,000
Amortization of operating lease right-of-use assets	3,633,000	2,641,000	0
Loss on extinguishment of debt	2,851,000	1,158,000	0
(Reversal of) provision for loan losses	(9,953,000)	18,447,000	4,224,000
Gain on securities transactions	(2,025,000)	(370,000)	(2,612,000)
Change in fair value of equity securities	1,792,000	(767,000)	(305,000)
Gain on securitizations	(2,259,000)	(3,544,000)	0
Gain on sale of loans	(8,531,000)	(1,900,000)	(785,000)
Loss on real estate owned	0	0	1,000
Loss on disposal of office properties and equipment	95,000	734,000	3,000
Loss on write-down of office properties and equipment	0	114,000	0
Loss on write-down of mortgage servicing rights	0	75,000	0
Deferred tax expense	17,709,000	9,738,000	7,527,000
Decrease (increase) in accrued interest receivable	2,023,000	(6,685,000)	(959,000)
(Increase) in other assets	(22,159,000)	(75,127,000)	(51,856,000)
(Decrease) increase in accrued expenses and other liabilities	1,926,000	32,891,000	3,032,000
Income on bank-owned life insurance	(5,994,000)	(6,620,000)	(5,846,000)
Employee stock ownership plan expense	4,052,000	3,161,000	3,566,000
Stock based compensation	8,880,000	8,790,000	3,694,000
Increase (decrease) in deferred compensation obligations under Rabbi Trust	3,000	(60,000)	65,000
Net cash provided by operating activities	98,704,000	49,044,000	21,824,000
Cash flows from investing activities:
Proceeds from sales of debt securities available for sale	90,339,000	20,761,000	65,198,000
Proceeds from sales of equity securities	1,390,000	0	1,065,000
Proceeds from paydown/maturities/calls of debt securities available for sale	368,249,000	247,908,000	149,683,000
Proceeds from paydown/maturities/calls of debt securities held to maturity	36,103,000	48,640,000	46,133,000
Purchases of debt securities available for sale	(667,015,000)	(292,809,000)	(176,171,000)
Purchases of debt securities held to maturity	(203,779,000)	(12,815,000)	(70,126,000)
Purchases of equity securities	(91,000)	0	(416,000)
Proceeds from sales of loans held-for-sale	302,039,000	111,764,000	101,946,000
Proceeds from sales of loans receivable	0	35,613,000	11,671,000
Purchases of loans receivable	(85,382,000)	0	(89,774,000)
Net increase in loans receivable	(325,917,000)	(80,498,000)	(503,772,000)
Proceeds from bank-owned life insurance death benefits	5,000	627,000	1,015,000
Proceeds from redemptions of Federal Home Loan Bank stock	28,448,000	50,374,000	72,871,000
Purchases of Federal Home Loan Bank stock	(4,798,000)	(22,544,000)	(79,796,000)
Proceeds from sales of office properties and equipment	1,879,000	0	0
Additions to office properties and equipment	(5,492,000)	(4,624,000)	(19,344,000)
Proceeds from sales of real estate owned	0	0	91,000
Net cash acquired in acquisitions	20,417,000	155,248,000	(31,288,000)
Net cash (used in) provided by investing activities	(443,605,000)	257,645,000	(521,014,000)
Cash flows from financing activities:
Net increase in deposits	581,475,000	799,548,000	449,270,000
Proceeds from long-term borrowings	37,120,000	90,000,000	140,000,000
Payments on long-term borrowings	(306,752,000)	(343,939,000)	(230,000,000)
Net (decrease) increase in short-term borrowings	(244,027,000)	(376,005,000)	225,081,000
Proceeds from term note	29,841,000	0	0
Payments of subordinated debt and trust preferred securities	0	(16,600,000)	0
Increase (decrease) in advance payments by borrowers for taxes and insurance	3,406,000	(3,919,000)	3,121,000
Issuance of common stock	0	0	14,000
Purchase of treasury stock	(107,774,000)	(108,166,000)	(55,309,000)
Exercise of options	(25,000)	0	0
Restricted stock forfeitures	0	(24,000)	(736,000)
Repurchase of shares for taxes	(357,000)	(174,000)	0
Issuance of treasury stock allocated to restricted stock award grants	0	0	1,095,000
Net cash (used in) provided by financing activities	(7,093,000)	40,721,000	532,536,000
Net (decrease) increase in cash and cash equivalents	(351,994,000)	347,410,000	33,346,000
Cash and cash equivalents at beginning of year	422,957,000	75,547,000	42,201,000
Cash and cash equivalents at end of year	70,963,000	422,957,000	75,547,000
Cash paid during the period for:
Interest on deposits and borrowings	37,906,000	75,557,000	87,370,000
Income tax payments, net of (refunds)	16,262,000	10,526,000	(2,893,000)
Non-cash investing and financing activities:
Transfer of loans receivable to loans held-for-sale	289,362,000	114,171,000	93,147,000
Securitization of loans	99,603,000	117,259,000	21,615,000
Initial recognition of operating lease right-of-use asset	0	22,218,000	0
Initial recognition of operating lease liabilities	0	23,290,000	0
Non-cash assets acquired:
Debt securities available for sale	118,017,000	51,479,000	51,710,000
Debt securities held to maturity	0	13,418,000	0
Equity securities	0	1,796,000	1,073,000
Federal Home Loan Bank stock	3,032,000	2,010,000	3,716,000
Loans receivable	158,912,000	171,593,000	757,223,000
Accrued interest receivable	867,000	679,000	2,239,000
Office properties and equipment, net	5,934,000	5,774,000	6,815,000
Bank-owned life insurance	8,661,000	17,245,000	22,096,000
Core deposit and other intangibles	42,000	0	7,467,000
Other assets	616,000	7,964,000	4,301,000
Total non-cash assets acquired	296,081,000	271,958,000	856,640,000
Liabilities assumed:
Deposits	210,117,000	333,234,000	782,698,000
Borrowings	59,908,000	37,728,000	82,761,000
Advance payments by borrowers for taxes and insurance	495,000	982,000	356,000
Accrued expenses and other liabilities	4,822,000	5,400,000	14,584,000
Total liabilities assumed	275,342,000	377,344,000	880,399,000
Net non-cash assets acquired (liabilities assumed)	20,739,000	(105,386,000)	(23,759,000)
Net cash and cash equivalents acquired in acquisitions	$ 20,417,000	$ 155,248,000	$ 105,006,000