Segment Information (Segment Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Interest Income	$ 28,548	$ 24,917	$ 81,627	$ 74,455
Net Gains on Sales of Loans	866	952	2,421	2,598
Net Gains on Securities	90	575	434	575
Trust and Investment Product Fees	1,585	1,301	5,035	3,894
Insurance Revenues	1,827	1,728	6,453	6,112
Noncash Items:
Provision for Loan Losses	500	250	2,070	1,100
Depreciation and Amortization	1,625	1,179	4,226	3,496
Income Tax Expense (Benefit)	2,796	3,511	7,606	10,757
Segment Profit (Loss)	12,639	9,660	35,549	29,055
Segment Assets	3,363,769		3,363,769		$ 3,144,360
Operating Segments | Core Banking
Segment Reporting Information [Line Items]
Net Interest Income	28,755	25,109	82,217	75,017
Net Gains on Sales of Loans	866	952	2,421	2,598
Net Gains on Securities	90	572	434	572
Trust and Investment Product Fees	1	0	3	2
Insurance Revenues	9	11	15	25
Noncash Items:
Provision for Loan Losses	500	250	2,070	1,100
Depreciation and Amortization	1,540	1,091	3,971	3,235
Income Tax Expense (Benefit)	2,825	3,669	7,556	10,906
Segment Profit (Loss)	12,462	9,621	34,702	28,377
Segment Assets	3,365,394		3,365,394		3,142,096
Operating Segments | Trust and Investment Advisory Services
Segment Reporting Information [Line Items]
Net Interest Income	2	2	4	4
Net Gains on Sales of Loans	0	0	0	0
Net Gains on Securities	0	0	0	0
Trust and Investment Product Fees	1,584	1,300	5,032	3,894
Insurance Revenues	31	2	35	15
Noncash Items:
Provision for Loan Losses	0	0	0	0
Depreciation and Amortization	2	5	4	12
Income Tax Expense (Benefit)	109	31	341	114
Segment Profit (Loss)	298	41	952	151
Segment Assets	2,700		2,700		1,987
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Net Interest Income	3	2	8	6
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	1,787	1,715	6,403	6,072
Noncash Items:
Provision for Loan Losses	0	0	0	0
Depreciation and Amortization	19	19	59	57
Income Tax Expense (Benefit)	52	67	386	542
Segment Profit (Loss)	147	102	1,116	849
Segment Assets	11,185		11,185		10,078
Other
Segment Reporting Information [Line Items]
Net Interest Income	(212)	(196)	(602)	(572)
Net Gains on Sales of Loans	0	0	0	0
Net Gains on Securities	0	3	0	3
Trust and Investment Product Fees	0	1	0	(2)
Insurance Revenues	0	0	0	0
Noncash Items:
Provision for Loan Losses	0	0	0	0
Depreciation and Amortization	64	64	192	192
Income Tax Expense (Benefit)	(190)	(256)	(677)	(805)
Segment Profit (Loss)	(268)	$ (104)	(1,221)	$ (322)
Segment Assets	$ (15,510)		$ (15,510)		$ (9,801)