Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest and fees on loans and leases:
Taxable		$ 183,568	$ 186,041	$ 166,304
Exempt from federal income taxes		9,537	10,942	9,889
Total interest and fees on loans and leases		193,105	196,983	176,193
Interest and dividends on investment securities:
Taxable		7,842	10,660	9,388
Exempt from federal income taxes		678	1,420	1,841
Interest on deposits with other banks		574	2,876	1,101
Interest and dividends on other earning assets		1,746	2,154	1,965
Total interest income		203,945	214,093	190,488
Interest expense
Interest on demand deposits		7,724	18,633	11,061
Interest on savings deposits		2,057	3,660	2,357
Interest on time deposits		9,835	13,276	8,768
Interest on short-term borrowings		327	1,012	2,420
Interest on long-term debt		9,641	8,280	7,820
Total interest expense		29,584	44,861	32,426
Net interest income	[1]	174,361	169,232	158,062
Provision for credit losses		40,794	8,511	20,310
Net interest income after provision for credit losses		133,567	160,721	137,752
Disaggregation of Revenue [Line Items]
Insurance commission and fee income		16,087	16,571	15,658
Bank owned life insurance income	[1]	2,940	3,179	3,174
Net gain on sales of investment securities	[1]	871	54	10
Net gain on mortgage banking activities	[1]	16,442	3,946	3,125
Other income	[2]	5,953	2,619	262
Total noninterest income		78,328	65,422	60,173
Noninterest expense
Salaries, benefits and commissions		93,208	88,289	80,488
Net occupancy		10,358	10,221	10,260
Equipment		3,841	4,170	4,146
Data processing		11,333	10,450	9,014
Professional fees		5,338	5,563	5,391
Marketing and advertising		1,975	2,594	2,642
Deposit insurance premiums		2,591	780	1,836
Intangible expenses		1,216	1,595	2,166
Restructuring charges		1,439	0	571
Other expense		23,699	22,428	20,725
Total noninterest expense		154,998	146,090	137,239
Income before income taxes		56,897	80,053	60,686
Income tax expense		9,981	14,334	10,143
Net income		$ 46,916	$ 65,719	$ 50,543
Net income per share:
Basic (in dollars per share)		$ 1.60	$ 2.24	$ 1.72
Diluted (in dollars per share)		$ 1.60	$ 2.24	$ 1.72
Trust fee income
Disaggregation of Revenue [Line Items]
Noninterest income		$ 7,703	$ 7,826	$ 7,882
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income		4,845	5,946	5,632
Investment advisory commission and fee income
Disaggregation of Revenue [Line Items]
Noninterest income		15,944	15,940	15,098
Other service fee income
Disaggregation of Revenue [Line Items]
Noninterest income	[2]	$ 7,543	$ 9,341	$ 9,332

[1] Net interest income as well as many other revenues for financial assets and liabilities including loans, leases, securities, and derivatives are excluded from the scope of FASB ASC 606 "Revenue from Contracts with Customers" (FASB ASC 606). Noninterest income streams that are out of scope of FASB ASC 606 include bank owned life insurance income, sales of investment securities and mortgage banking activities.

[2] Other service fee income and other income include certain items that are in scope and certain items that are out of scope of FASB ASC 606 are described further in the following paragraphs.