Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INTEREST AND DIVIDEND INCOME
Loans, including fees	$ 465,677	$ 393,166	$ 331,961
Interest and dividends on securities:
Taxable	53,594	65,648	56,898
Tax-exempt	16,999	20,006	20,778
Total interest and dividends on securities	70,593	85,654	77,676
Other interest income	5,007	5,433	5,320
Total interest and dividend income	541,277	484,253	414,957
INTEREST EXPENSE
Interest bearing demand deposits	7,069	16,805	13,144
Money market deposits	4,616	8,024	5,016
Savings deposits	1,802	2,995	1,225
Certificates of deposit	13,562	15,631	12,450
Total interest expense on deposits	27,049	43,455	31,835
Federal Home Loan Bank borrowings	24,701	26,548	23,333
Other short-term borrowings	1,729	5,401	3,717
Subordinated debt and junior subordinated debt	8,318	8,945	8,836
Total interest expense	61,797	84,349	67,721
NET INTEREST INCOME	479,480	399,904	347,236
Provision for credit losses	107,741	11,198	7,764
Net interest income after provision for credit losses	371,739	388,706	339,472
NON-INTEREST INCOME
Electronic banking fees	17,524	22,634	23,300
Net securities brokerage revenue	6,189	6,990	7,186
Bank-owned life insurance	7,359	5,913	6,427
Mortgage banking income	22,736	8,219	5,840
Net securities gains (losses)	4,268	4,320	(900)
Net gains on other real estate owned and other assets	103	732	524
Other income	21,728	14,355	9,606
Total non-interest income	128,185	116,716	100,276
NON-INTEREST EXPENSE
Salaries and wages	153,166	132,485	114,602
Employee benefits	41,723	39,313	30,079
Net occupancy	27,580	22,505	19,165
Equipment	24,801	20,494	17,207
Marketing	5,957	6,062	5,368
FDIC insurance	7,734	1,956	3,242
Amortization of intangible assets	13,411	10,340	6,980
Restructuring and merger-related expense	9,725	16,397	17,860
Other operating expenses	70,748	62,656	50,721
Total non-interest expense	354,845	312,208	265,224
Income before provision for income taxes	145,079	193,214	174,524
Provision for income taxes	23,035	34,341	31,412
NET INCOME	122,044	158,873	143,112
Preferred stock dividends	2,644
NET INCOME AVAILABLE TO COMMON SHAREHOLDERS	$ 119,400	$ 158,873	$ 143,112
EARNINGS PER COMMON SHARE
Basic	$ 1.78	$ 2.83	$ 2.93
Diluted	$ 1.77	$ 2.83	$ 2.92
AVERAGE COMMON SHARES OUTSTANDING
Basic	67,260,796	56,108,084	48,889,041
Diluted	67,310,584	56,214,364	49,022,990
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.28	$ 1.24	$ 1.16
Total Trust Fees [Member]
NON-INTEREST INCOME
NON-INTEREST INCOME	$ 26,335	$ 26,579	$ 24,623
Service Charges on Deposits [Member]
NON-INTEREST INCOME
NON-INTEREST INCOME	$ 21,943	$ 26,974	$ 23,670