Parent Company Financial Statements (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 10,980	$ 12,639	$ 11,097	$ 11,813	$ 11,621	$ 9,660	$ 9,839	$ 9,556	$ 46,529	$ 40,676	$ 35,184
Adjustments to Reconcile Net Income to Net Cash from Operations
Interest Receivable and Other Assets									2,211	(4,528)	5,813
Change in Other Liabilities									(162)	(110)	(2,547)
Equity Based Compensation									1,355	1,246	1,407
Excess Tax Benefit from Restricted Share Grant									32	240	200
Net Cash from Operating Activities									62,331	54,875	41,913
CASH FLOWS FROM INVESTING ACTIVITIES
Cash Used for Business Acquisitions									0	0	(1,016)
Net Cash from Investing Activities									(38,798)	(189,280)	(71,689)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Issuance of Long-term Debt									25,000	75,000	0
Issuance (Retirement) of Common Stock										(29)	55
Dividends Paid									(14,074)	(11,842)	(10,630)
Net Cash from Financing Activities									2,658	139,948	42,583
Net Change in Cash and Cash Equivalents									26,191	5,543	12,807
Cash and Cash Equivalents at Beginning of Year				70,359				64,816	70,359	64,816	52,009
Cash and Cash Equivalents at End of Year	96,550				70,359				96,550	70,359	64,816
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income									46,529	40,676	35,184
Adjustments to Reconcile Net Income to Net Cash from Operations
Interest Receivable and Other Assets									1,588	431	2,085
Change in Other Liabilities									(163)	(122)	310
Equity Based Compensation									1,355	1,246	1,407
Excess Tax Benefit from Restricted Share Grant									32	240	200
Equity in Excess Undistributed Income of Subsidiaries									(42,016)	(16,040)	(21,514)
Net Cash from Operating Activities									7,325	26,431	17,672
CASH FLOWS FROM INVESTING ACTIVITIES
Cash Used for Business Acquisitions									(25,160)	0	(15,992)
Net Cash from Investing Activities									(25,160)	0	(15,992)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Issuance of Long-term Debt									25,000	0	0
Issuance (Retirement) of Common Stock									0	(29)	55
Dividends Paid									(14,074)	(11,842)	(10,630)
Net Cash from Financing Activities									10,926	(11,871)	(10,575)
Net Change in Cash and Cash Equivalents									(6,909)	14,560	(8,895)
Cash and Cash Equivalents at Beginning of Year				$ 24,777				$ 10,217	24,777	10,217	19,112
Cash and Cash Equivalents at End of Year	$ 17,868				$ 24,777				$ 17,868	$ 24,777	$ 10,217