Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest and fees on loans and leases:
Taxable		$ 186,041	$ 166,304	$ 143,176
Exempt from federal income taxes		10,942	9,889	8,442
Total interest and fees on loans and leases		196,983	176,193	151,618
Interest and dividends on investment securities:
Taxable		10,660	9,388	7,343
Exempt from federal income taxes		1,420	1,841	2,274
Interest on deposits with other banks		2,876	1,101	280
Interest and dividends on other earning assets		2,154	1,965	1,500
Total interest income		214,093	190,488	163,015
Interest expense
Interest on demand deposits		18,633	11,061	3,917
Interest on savings deposits		3,660	2,357	2,089
Interest on time deposits		13,276	8,768	5,271
Interest on short-term borrowings		1,012	2,420	904
Interest on long-term debt and subordinated notes		8,280	7,820	7,658
Total interest expense		44,861	32,426	19,839
Net interest income	[1]	169,232	158,062	143,176
Provision for loan and lease losses		8,518	20,310	9,892
Net interest income after provision for loan and lease losses		160,714	137,752	133,284
Disaggregation of Revenue [Line Items]
Insurance commission and fee income		16,571	15,658	14,788
Bank owned life insurance income	[1]	3,179	3,174	3,988
Net gain on sales of investment securities	[1]	54	10	48
Net gain on mortgage banking activities	[1]	3,946	3,125	4,023
Other income	[2]	2,619	262	746
Total noninterest income		65,422	60,173	59,240
Noninterest expense
Salaries, benefits and commissions		88,289	80,488	75,890
Net occupancy		10,221	10,260	10,433
Equipment		4,170	4,146	4,118
Data processing		10,450	9,014	8,500
Professional fees		5,563	5,391	5,325
Marketing and advertising		2,594	2,642	2,205
Deposit insurance premiums		780	1,836	1,636
Intangible expenses		1,595	2,166	2,582
Restructuring charges		0	571	0
Other expense		22,421	20,725	20,024
Total noninterest expense		146,083	137,239	130,713
Income before income taxes		80,053	60,686	61,811
Income taxes		14,334	10,143	17,717
Net income		$ 65,719	$ 50,543	$ 44,094
Net income per share:
Basic (in dollars per share)		$ 2.24	$ 1.72	$ 1.64
Diluted (in dollars per share)		$ 2.24	$ 1.72	$ 1.64
Trust fee income
Disaggregation of Revenue [Line Items]
Noninterest income		$ 7,826	$ 7,882	$ 8,055
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income		5,946	5,632	5,482
Investment advisory commission and fee income
Disaggregation of Revenue [Line Items]
Noninterest income		15,940	15,098	13,454
Other service fee income
Disaggregation of Revenue [Line Items]
Noninterest income	[2]	$ 9,341	$ 9,332	$ 8,656

[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.