Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income	$ 120,992,000	$ 121,167,000	$ 165,175,000
Depreciation, Depletion and Amortization, Nonproduction	32,824,000	27,262,000	19,439,000
Change In Unamortized Net Loan Costs And Premiums	(24,785,000)	(7,126,000)	2,692,000
Accretion of acquired loans	(6,882,000)	(6,286,000)	(12,778,000)
Provision for credit losses	18,205,000	52,500,000	6,000,000
Deferred income tax expense	3,090,000	(17,506,000)	10,594,000
Equity Securities, FV-NI, Gain (Loss)	(554,000)	(528,000)	(1,566,000)
Gain (Loss) on Investments			1,462,000
Gain (Loss) on Disposition of Property Plant Equipment	139,000	372,000	(474,000)
Operating Lease, Impairment Loss	0	4,163,000	0
Loss on Derivative Instruments, Pretax	0	684,000	0
Net loss on other real estate owned and foreclosed assets	0	0	401,000
Sale and Leaseback Transaction, Gain (Loss), Net	578,000	578,000	578,000
Share-based Payment Arrangement, Noncash Expense	4,309,000	4,123,000	4,403,000
Life Insurance, Corporate or Bank Owned, Change in Value	(6,431,000)	(5,362,000)	(5,013,000)
Gain Realized on Life Insurance Policies	(258,000)	(1,044,000)	(434,000)
Operating Lease, Payments	(17,456,000)	(11,936,000)	(10,669,000)
Change in Fair Value on Loans Held for Sale	1,679,000	(1,296,000)	(822,000)
Increase (Decrease) in Debt Securities, Trading, and Equity Securities, FV-NI	(882,000)	(659,000)	(675,000)
Increase (Decrease) in Loans Held-for-sale	31,746,000	(23,501,000)	59,932,000
Increase (Decrease) in Other Operating Assets	93,565,000	(145,953,000)	(39,850,000)
Change in other liabilities	(58,503,000)	76,140,000	19,283,000
Total adjustments	69,228,000	(56,531,000)	51,347,000
Net cash provided by operating activities	190,220,000	64,636,000	216,522,000
Proceeds from Sale of Debt and Equity Securities, FV-NI, Held-for-investment	1,164,000	0	1,461,000
Increase (Decrease) in Equity Securities, FV-NI	(2,171,000)	(803,000)	(711,000)
Proceeds from Sale of Debt Securities, Available-for-sale	0	0	45,863,000
Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale	95,981,000	108,893,000	51,104,000
Payments to Acquire Debt Securities, Available-for-sale	(1,284,867,000)	(84,156,000)	(68,677,000)
Proceeds from maturities and principal repayments of securities held to maturity	263,106,000	261,705,000	126,991,000
Payments to Acquire Held-to-maturity Securities	(606,543,000)	(244,718,000)	(59,967,000)
Net redemption of Federal Home Loan Bank stock	25,027,000	4,174,000	18,896,000
Investments in low income housing projects	(22,496,000)	(17,858,000)	(10,052,000)
Purchases of life insurance policies	(40,164,000)	(164,000)	(163,000)
Proceeds from Life Insurance Policy	576,000	3,417,000	3,162,000
Payments for (Proceeds from) Loans and Leases	744,981,000	(511,526,000)	27,816,000
Cash Acquired in Excess of Payments to Acquire Business	787,301,000
Net cash acquired (paid) in business combinations		0	(105,264,000)
Payments to Acquire Property, Plant, and Equipment	(25,200,000)	(12,586,000)	(16,583,000)
Proceeds from Sale of Property, Plant, and Equipment	169,000	6,095,000	3,796,000
Payments on early termination of hedging relationship	0	(684,000)	0
Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans	0	0	2,488,000
Net cash provided by (used in) investing activities	(63,136,000)	(488,211,000)	20,160,000
Increase (Decrease) in Time Deposits	(235,577,000)	(444,276,000)	(45,272,000)
Increase (Decrease) in Other Deposits	1,719,398,000	2,290,489,000	(160,637,000)
Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net	0	(45,000,000)	(132,046,000)
Increase Decrease in Federal Home Loan Bank Advances Long Term	(586,088,000)	(35,000,000)	(25,000,000)
Proceeds from Lines of Credit	0	0	49,980,000
Repayments of Lines of Credit	0	0	(49,980,000)
Repayments of Long-term Debt	(18,750,000)	(42,187,000)
Proceeds from Issuance of Debt			(74,867,000)
RepaymentsOfJuniorSubordinatedDebt	0	0	(13,329,000)
Proceeds from Issuance of Subordinated Long-term Debt	0	0	49,526,000
Repayments of Subordinated Debt	0	0	(34,767,000)
Net payments from exercise of stock options	(57,000)
Cash received from stock option exercises		(197,000)	(281,000)
Issuance Of Restricted Stock Awards, Net of Issuance Cost	(1,249,000)	(1,187,000)	(1,463,000)
Proceeds from shares issued under the direct stock purchase plan	2,023,000	2,132,000	4,951,000
Payments for Repurchase of Common Stock	0	(95,091,000)	0
Common dividends paid	(62,736,000)	(60,840,000)	(53,274,000)
Net cash provided by (used in) financing activities	816,964,000	1,569,237,000	(336,163,000)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	944,048,000	1,145,662,000	(99,481,000)
Cash and cash equivalents at beginning of year	1,296,636,000	150,974,000	250,455,000
Cash and cash equivalents at end of period	2,240,684,000	1,296,636,000	150,974,000
Supplemental schedule of noncash investing and financing activities
Interest Paid, Excluding Capitalized Interest, Operating Activities	14,004,000	36,739,000	49,704,000
Income taxes	23,353,000	48,240,000	39,575,000
Capital commitment relating to Low Income Housing Project investments, noncash	33,691,000	32,477,000	36,543,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	7,768,000	8,646,000	14,951,000
Operating Lease, Right-of-Use Asset	60,200,000	49,700,000
Operating Lease, Liability	63,908,000
In conjunction with the Company's acquisitions, assets were acquired and liabilities were assumed as follows
Common stock issued for acquisition	1,298,558,000	0	499,693,000
Fair value of assets acquired, net of cash acquired	5,574,209,000	0	2,711,067,000
Fair value of liabilities assumed	$ 5,062,952,000	$ 0	$ 2,106,110,000