Consolidated Statements of Cash Flows	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Net income	$ 121,167,000	$ 165,175,000	$ 121,622,000
Depreciation, Depletion and Amortization, Nonproduction	27,262,000	19,439,000	15,629,000
Change In Unamortized Net Loan Costs And Premiums	(13,412,000)	(10,086,000)	365,000
Provision for credit losses	52,500,000	6,000,000	4,775,000
Deferred income tax expense	(17,506,000)	10,594,000	(4,497,000)
Equity Securities, FV-NI, Gain (Loss)	(528,000)	(1,566,000)	1,225,000
Gain (Loss) on Investments		1,462,000
Gain (Loss) on Disposition of Property Plant Equipment	372,000	(474,000)	(1,126,000)
Operating Lease, Impairment Loss	4,163,000	0	0
Loss on Derivative Instruments, Pretax	684,000	0	0
Net loss on other real estate owned and foreclosed assets	0	401,000	112,000
Sale Leaseback Transaction, Current Period Gain Recognized	(578,000)	(578,000)	(730,000)
Share-based Payment Arrangement, Noncash Expense	4,123,000	4,403,000	4,225,000
Life Insurance, Corporate or Bank Owned, Change in Value	(5,362,000)	(5,013,000)	(4,060,000)
Gain Realized on Life Insurance Policies	(1,044,000)	(434,000)	(1,463,000)
Operating Lease, Payments	(11,936,000)	(10,669,000)	0
Change in Fair Value on Loans Held for Sale	(1,296,000)	(822,000)	51,000
Increase (Decrease) in Debt Securities, Trading, and Equity Securities, FV-NI	(659,000)	(675,000)	(180,000)
Increase (Decrease) in Loans Held-for-sale	(23,501,000)	59,932,000	(1,714,000)
Increase (Decrease) in Other Operating Assets	(145,953,000)	(39,850,000)	503,000
Change in other liabilities	76,140,000	19,283,000	7,100,000
Total adjustments	(56,531,000)	51,347,000	20,215,000
Net cash provided by operating activities	64,636,000	216,522,000	141,837,000
Proceeds from Sale of Debt and Equity Securities, FV-NI, Held-for-investment	0	1,461,000	5,752,000
Increase (Decrease) in Equity Securities, FV-NI	(803,000)	(711,000)	(6,315,000)
Proceeds from Sale of Debt Securities, Available-for-sale		45,863,000
Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale	108,893,000	51,104,000	82,418,000
Payments to Acquire Debt Securities, Available-for-sale	(84,156,000)	(68,677,000)	(78,990,000)
Proceeds from maturities and principal repayments of securities held to maturity	261,705,000	126,991,000	82,355,000
Payments to Acquire Held-to-maturity Securities	(244,718,000)	(59,967,000)	(195,538,000)
Net redemption (purchases) of Federal Home Loan Bank stock	4,174,000	18,896,000	(2,376,000)
Investments in low income housing projects	(17,858,000)	(10,052,000)	(3,434,000)
Purchases of life insurance policies	(164,000)	(163,000)	(164,000)
Proceeds from Life Insurance Policy	3,417,000	3,162,000	2,850,000
Payments for (Proceeds from) Loans and Leases	(511,526,000)	27,816,000	(258,633,000)
Net cash paid in business combinations	0	(105,264,000)	(6,906,000)
Payments to Acquire Property, Plant, and Equipment	(12,586,000)	(16,583,000)	(11,106,000)
Proceeds from Sale of Property, Plant, and Equipment	6,095,000	3,796,000	2,189,000
Payments on early termination of hedging relationship	(684,000)	0	0
Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans		2,488,000	387,000
Net cash provided by (used in) investing activities	(488,211,000)	20,160,000	(387,511,000)
Increase (Decrease) in Time Deposits	(444,276,000)	(45,272,000)	(1,430,000)
Increase (Decrease) in Other Deposits	2,290,489,000	(160,637,000)	280,017,000
Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net	(45,000,000)	(132,046,000)	67,046,000
Increase Decrease in Federal Home Loan Bank Advances Long Term	(35,000,000)	(25,000,000)	(2,475,000)
Net decrease in customer repurchase agreements			(21,503,000)
Proceeds from Lines of Credit	0	49,980,000	0
Repayments of Lines of Credit	0	(49,980,000)	0
Repayments of Long-term Debt	(42,187,000)
Proceeds from Issuance of Debt		74,867,000	0
RepaymentsOfJuniorSubordinatedDebt	0	(13,329,000)	0
Proceeds from Issuance of Subordinated Long-term Debt	0	49,526,000	0
Repayments of Subordinated Debt	0	(34,767,000)	0
Cash received from stock option exercises	197,000	281,000	184,000
Issuance Of Restricted Stock Awards, Net of Issuance Cost	(1,187,000)	(1,463,000)	(1,371,000)
Proceeds from shares issued under the direct stock purchase plan	2,132,000	4,951,000	2,712,000
Payments for Repurchase of Common Stock	(95,091,000)	0	0
Common dividends paid	(60,840,000)	(53,274,000)	(40,167,000)
Net cash provided by (used in) financing activities	1,569,237,000	(336,163,000)	283,013,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	1,145,662,000	(99,481,000)	37,339,000
Cash and cash equivalents at beginning of year	150,974,000	250,455,000	213,116,000
Cash and cash equivalents at end of period	1,296,636,000	150,974,000	250,455,000
Supplemental schedule of noncash investing and financing activities
Interest Paid, Excluding Capitalized Interest, Operating Activities	36,739,000	49,704,000	25,337,000
Income taxes	48,240,000	39,575,000	27,809,000
Capital commitment relating to Low Income Housing Project investments, noncash	32,477,000	36,543,000	2,833,000
Transfer of customer repurchase agreements to deposits noncash	0	0	141,176,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	8,646,000	14,951,000	0
Operating Lease, Right-of-Use Asset	49,700,000	56,600,000
Operating Lease, Liability	56,356,000	16,393,000
In conjunction with the Company's acquisitions, assets were acquired and liabilities were assumed as follows
Common stock issued for acquisition	0	499,693,000	42,474,000
Fair value of assets acquired, net of cash acquired	0	2,711,067,000	362,286,000
Fair value of liabilities assumed	$ 0	$ 2,106,110,000	$ 312,906,000