Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating activities
Net income	$ 195,457,000	$ 144,678,000	$ 166,068,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	9,273,000	15,593,000	23,871,000
Depreciation, amortization and accretion	32,284,000	35,231,000	42,744,000
Deferred income tax expense (benefit)	4,649,000	(5,005,000)	2,280,000
Impairment losses on securities	0	19,352,000	0
Proceeds from sale of mortgage servicing rights	23,011,000	0	18,525,000
Gain on sale of mortgage servicing rights	(3,472,000)	(547,000)	(2,960,000)
Gain on sale of insurance agency	(53,349,000)	0	0
Funding of mortgage loans held for sale	(1,400,467,000)	(1,330,912,000)	(1,679,356,000)
Proceeds from sales of mortgage loans held for sale	1,347,659,000	1,277,363,000	2,043,360,000
Gains on sales of mortgage loans held for sale	(16,611,000)	(14,573,000)	(15,803,000)
Losses on sales of securities	0	22,438,000	0
Gain on debt extinguishment	(56,000)	(620,000)	0
Losses (gains) on sales of premises and equipment	33,000	(173,000)	(239,000)
Stock-based compensation	13,883,000	13,716,000	11,505,000
Increase in other assets	(15,014,000)	(51,986,000)	(29,671,000)
(Decrease) increase in other liabilities	(7,854,000)	23,998,000	(6,279,000)
Net cash provided by operating activities	129,426,000	148,553,000	574,045,000
Investing activities
Purchases of securities available for sale	(174,229,000)	(11,899,000)	(713,096,000)
Proceeds from sales of securities available for sale	177,185,000	488,981,000	0
Proceeds from call/maturities of securities available for sale	88,830,000	149,025,000	385,507,000
Purchases of securities held to maturity	0	0	(91,803,000)
Proceeds from call/maturities of securities held to maturity	102,178,000	109,953,000	67,448,000
Net increase in loans	(543,495,000)	(791,803,000)	(1,456,119,000)
Purchases of premises and equipment	(13,645,000)	(21,634,000)	(14,838,000)
Proceeds from sales of premises and equipment	344,000	943,000	1,234,000
Net cash received from sale of insurance agency	55,333,000	0	0
Purchase of bank-owned life insurance	0	0	(80,000,000)
Net change in FHLB stock	4,795,000	16,076,000	(27,807,000)
Proceeds from sales of other assets	3,350,000	3,115,000	3,578,000
Net cash paid in acquisitions	0	0	(120,888,000)
Other, net	1,313,000	1,844,000	3,127,000
Net cash used in investing activities	(298,041,000)	(55,399,000)	(2,043,657,000)
Financing activities
Net decrease in noninterest-bearing deposits	(179,694,000)	(975,081,000)	(159,368,000)
Net increase (decrease) in interest-bearing deposits	675,521,000	1,564,900,000	(259,390,000)
Net (decrease) increase in short-term borrowings	(199,559,000)	(404,655,000)	668,805,000
Repayment of long-term debt	(245,000)	(2,680,000)	(32,417,000)
Cash paid for dividends	(53,727,000)	(50,279,000)	(49,991,000)
Proceeds from equity offering	217,000,000	0	0
Net cash provided by financing activities	459,296,000	132,205,000	167,639,000
Net increase (decrease) in cash and cash equivalents	290,681,000	225,359,000	(1,301,973,000)
Cash and cash equivalents at beginning of year	801,351,000	575,992,000	1,877,965,000
Cash and cash equivalents at end of year	1,092,032,000	801,351,000	575,992,000
Supplemental disclosures
Cash paid for interest	381,004,000	239,611,000	54,562,000
Cash paid for income taxes	29,065,000	42,047,000	41,764,000
Noncash transactions:
Transfers of loans to other real estate	5,037,000	10,738,000	2,207,000
Recognition of operating right-of-use assets	4,630,000	3,126,000	3,475,000
Recognition of operating lease liabilities	4,630,000	3,126,000	3,475,000
Available for sale securities transferred to held to maturity securities	$ 0	$ 0	$ 882,927,000