Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash dividends declared	$ 2.29	$ 2.20	$ 1.98
Total Shareholders’ Equity	$ 701,106	$ 657,983	$ 600,764
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Cash dividends declared	$ 2.29	$ 2.20	$ 1.98
Exercise of stock options	4,921	11,721	29,633
Purchase of treasury shares	573,000	261,000	290,000
Cumulative Effect, Period of Adoption, Adjustment
Total Shareholders’ Equity		$ (2,335)
Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		655,648
Retained Earnings [Member]
Total Shareholders’ Equity	$ 589,988	539,253	$ 485,967
Retained Earnings [Member] | Cumulative Effect, Period of Adoption, Adjustment
Total Shareholders’ Equity		(2,335)
Retained Earnings [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		536,918
Common Stock [Member]
Total Shareholders’ Equity	47,619	47,619	47,619
Common Stock [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		47,619
Capital Surplus[Member]
Total Shareholders’ Equity	171,304	170,309	169,555
Capital Surplus[Member] | Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		170,309
Treasury Stock, Common [Member]
Total Shareholders’ Equity	(139,038)	(105,038)	(87,895)
Treasury Stock, Common [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		(105,038)
Accumulated Other Comprehensive Income (Loss) [Member]
Total Shareholders’ Equity	$ 31,233	5,840	$ (14,482)
Accumulated Other Comprehensive Income (Loss) [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance
Total Shareholders’ Equity		$ 5,840
Poage Bankshares, Inc. [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares			1,142,000