Segment Information (Segment Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net Interest Income	$ 38,578			$ 28,548			$ 105,810	$ 81,627
Net Gains on Sales of Loans	1,649			866			3,660	2,421
Net Gains on Securities	313			90			984	434
Trust and Investment Product Fees	1,885			1,585			5,365	5,035
Insurance Revenues	1,883			1,827			7,017	6,453
Noncash Items:
Provision for Loan Losses	2,800			500			3,725	2,070
Depreciation and Amortization	2,291			1,625			6,364	4,226
Income Tax Expense (Benefit)	2,809			2,796			8,568	7,606
Segment Profit (Loss)	13,064	$ 15,271	$ 15,067	12,639	$ 11,097	$ 11,813	43,402	35,549
Segment Assets	4,355,882						4,355,882		$ 3,929,090
Operating Segments | Core Banking
Segment Reporting Information [Line Items]
Net Interest Income	39,302			28,755			107,619	82,217
Net Gains on Sales of Loans	1,649			866			3,660	2,421
Net Gains on Securities	313			90			984	434
Trust and Investment Product Fees	1			1			3	3
Insurance Revenues	14			9			21	15
Noncash Items:
Provision for Loan Losses	2,800			500			3,725	2,070
Depreciation and Amortization	2,196			1,540			6,099	3,971
Income Tax Expense (Benefit)	3,025			2,825			9,117	7,556
Segment Profit (Loss)	13,538			12,462			43,105	34,702
Segment Assets	4,345,551						4,345,551		3,926,242
Operating Segments | Trust and Investment Advisory Services
Segment Reporting Information [Line Items]
Net Interest Income	4			2			10	4
Net Gains on Sales of Loans	0			0			0	0
Net Gains on Securities	0			0			0	0
Trust and Investment Product Fees	1,884			1,584			5,362	5,032
Insurance Revenues	2			31			27	35
Noncash Items:
Provision for Loan Losses	0			0			0	0
Depreciation and Amortization	1			2			4	4
Income Tax Expense (Benefit)	137			109			341	341
Segment Profit (Loss)	406			298			993	952
Segment Assets	3,524						3,524		2,658
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Net Interest Income	5			3			14	8
Net Gains on Sales of Loans	0			0			0	0
Net Gains on Securities	0			0			0	0
Trust and Investment Product Fees	0			0			0	0
Insurance Revenues	1,867			1,787			6,969	6,403
Noncash Items:
Provision for Loan Losses	0			0			0	0
Depreciation and Amortization	14			19			53	59
Income Tax Expense (Benefit)	51			52			458	386
Segment Profit (Loss)	145			147			1,382	1,116
Segment Assets	8,904						8,904		11,368
Other
Segment Reporting Information [Line Items]
Net Interest Income	(733)			(212)			(1,833)	(602)
Net Gains on Sales of Loans	0			0			0	0
Net Gains on Securities	0			0			0	0
Trust and Investment Product Fees	0			0			0	0
Insurance Revenues	0			0			0	0
Noncash Items:
Provision for Loan Losses	0			0			0	0
Depreciation and Amortization	80			64			208	192
Income Tax Expense (Benefit)	(404)			(190)			(1,348)	(677)
Segment Profit (Loss)	(1,025)			$ (268)			(2,078)	$ (1,221)
Segment Assets	$ (2,097)						$ (2,097)		$ (11,178)