Parent Company Financial Statements (Condensed Statements of Cash Flows) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jun. 25, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income		$ 15,820	$ 13,064	$ 15,271	$ 15,067	$ 10,980	$ 12,639	$ 11,097	$ 11,813	$ 59,222	$ 46,529	$ 40,676
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:
Interest Receivable and Other Assets										(1,602)	2,211	(4,528)
Change in Other Liabilities										4,488	(162)	(110)
Equity Based Compensation										1,287	1,355	1,246
Excess Tax Benefit from Restricted Share Grant										25	32	240
Net Cash from Operating Activities										65,229	62,331	54,875
CASH FLOWS FROM INVESTING ACTIVITIES
Cash Used for Business Acquisitions										0	(17,566)	0
Net Cash from Investing Activities										30,662	(38,798)	(189,280)
CASH FLOWS FROM FINANCING ACTIVITIES
Advances in Long-term Debt										89,214	25,000	75,000
Repayments of Long-term Debt										(65,171)	(40,155)	(53,864)
Issuance (Retirement) of Common Stock												(29)
Dividends Paid										(17,556)	(14,074)	(11,842)
Net Cash from Financing Activities										(88,557)	2,658	139,948
Net Change in Cash and Cash Equivalents										7,334	26,191	5,543
Cash and Cash Equivalents at Beginning of Year					96,550				70,359	96,550	70,359	64,816
Cash and Cash Equivalents at End of Year		103,884				96,550				103,884	96,550	70,359
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income										59,222	46,529	40,676
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:
Interest Receivable and Other Assets										31	1,588	431
Change in Other Liabilities										(406)	(163)	(122)
Equity Based Compensation										1,287	1,355	1,246
Excess Tax Benefit from Restricted Share Grant										25	32	240
Equity in Excess Undistributed Income of Subsidiaries										(16,988)	(42,016)	(16,040)
Net Cash from Operating Activities										43,171	7,325	26,431
CASH FLOWS FROM INVESTING ACTIVITIES
Cash Used for Business Acquisitions										(14,958)	(25,160)	0
Net Cash from Investing Activities										(14,958)	(25,160)	0
CASH FLOWS FROM FINANCING ACTIVITIES
Advances in Long-term Debt										39,213	25,000	0
Repayments of Long-term Debt	$ (25,000)									(25,000)	0	0
Issuance (Retirement) of Common Stock										0		(29)
Dividends Paid										(17,556)	(14,074)	(11,842)
Net Cash from Financing Activities										(3,343)	10,926	(11,871)
Net Change in Cash and Cash Equivalents										24,870	(6,909)	14,560
Cash and Cash Equivalents at Beginning of Year					$ 17,868				$ 24,777	17,868	24,777	10,217
Cash and Cash Equivalents at End of Year		$ 42,738				$ 17,868				$ 42,738	$ 17,868	$ 24,777