Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($) office	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment office	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of primary segments | segment									3
Net Interest Income	$ 39,415	$ 38,578	$ 33,641	$ 33,591	$ 32,983	$ 28,548	$ 27,469	$ 25,610	$ 145,225	$ 114,610	$ 99,909
Net Gains on Sales of Loans									4,633	3,004	3,280
Net Gains on Securities									1,248	706	596
Trust and Investment Product Fees									7,278	6,680	5,272
Insurance Revenues									8,940	8,330	7,979
Noncash Items:
Provision for Loan Losses									5,325	2,070	1,750
Depreciation and Amortization									8,630	6,184	4,687
Income Tax Expense (Benefit)									12,017	9,528	11,534
Segment Profit (Loss)	15,820	$ 13,064	$ 15,271	$ 15,067	10,980	$ 12,639	$ 11,097	$ 11,813	59,222	46,529	40,676
Segment Assets	4,397,672				3,929,090				4,397,672	3,929,090	3,144,360
Other
Segment Reporting Information [Line Items]
Net Interest Income									(2,543)	(1,118)	(765)
Net Gains on Sales of Loans									0	0	0
Net Gains on Securities									0	0	3
Trust and Investment Product Fees									0	0	(3)
Insurance Revenues									0	0	0
Noncash Items:
Provision for Loan Losses									0	0	0
Depreciation and Amortization									288	256	256
Income Tax Expense (Benefit)									(1,687)	(1,020)	(1,385)
Segment Profit (Loss)									(2,475)	(2,121)	21
Segment Assets	$ 2,977				(11,178)				$ 2,977	(11,178)	(9,801)
Core Banking
Segment Reporting Information [Line Items]
Number of banking offices | office	76								76
Core Banking | Operating Segments
Segment Reporting Information [Line Items]
Net Interest Income									$ 147,735	115,710	100,659
Net Gains on Sales of Loans									4,633	3,004	3,280
Net Gains on Securities									1,248	706	593
Trust and Investment Product Fees									4	4	3
Insurance Revenues									25	17	28
Noncash Items:
Provision for Loan Losses									5,325	2,070	1,750
Depreciation and Amortization									8,265	5,847	4,351
Income Tax Expense (Benefit)									12,724	9,671	12,262
Segment Profit (Loss)									58,793	46,075	39,520
Segment Assets	$ 4,381,945				3,926,242				4,381,945	3,926,242	3,142,096
Trust and Investment Advisory Services | Operating Segments
Segment Reporting Information [Line Items]
Net Interest Income									15	5	6
Net Gains on Sales of Loans									0	0	0
Net Gains on Securities									0	0	0
Trust and Investment Product Fees									7,274	6,676	5,272
Insurance Revenues									28	40	34
Noncash Items:
Provision for Loan Losses									0	0	0
Depreciation and Amortization									6	5	4
Income Tax Expense (Benefit)									469	437	145
Segment Profit (Loss)									1,366	1,263	217
Segment Assets	3,670				2,658				3,670	2,658	1,987
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Net Interest Income									18	13	9
Net Gains on Sales of Loans									0	0	0
Net Gains on Securities									0	0	0
Trust and Investment Product Fees									0	0	0
Insurance Revenues									8,887	8,273	7,917
Noncash Items:
Provision for Loan Losses									0	0	0
Depreciation and Amortization									71	76	76
Income Tax Expense (Benefit)									511	440	512
Segment Profit (Loss)									1,538	1,312	918
Segment Assets	$ 9,080				$ 11,368				$ 9,080	$ 11,368	$ 10,078