CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common stock amount Impact of CECL Adoption	Common stock amount	Additional paid-in capital Impact of CECL Adoption	Additional paid-in capital	Retained earnings Impact of CECL Adoption	Retained earnings	Accumulated other comprehensive income (loss) Impact of CECL Adoption	Accumulated other comprehensive income (loss)	Treasury stock Impact of CECL Adoption	Treasury stock	Impact of CECL Adoption	Total
Balance at beginning of period at Dec. 31, 2019		$ 32,857		$ 188,536		$ 175,780		$ 3,792		$ (4,677)		$ 396,288
Increase (Decrease) in Stockholders' Equity
Net income		0		0		16,202		0		0		16,202
Other comprehensive (loss) income		0		0		0		(924)		0		(924)
Cash dividends declared		0		0		(6,819)		0		0		(6,819)
Treasury stock purchased		0		0		0		0		(7,467)		(7,467)
Net issuance to employee stock plans, including related tax effects		0		406		0		0		251		657
Recognition of stock based compensation		0		584		0		0		0		584
Balance at end of period at Jun. 30, 2020		32,857		189,526		185,163		2,868		(11,893)		398,521
Balance at beginning of period at Dec. 31, 2019		32,857		188,536		175,780		3,792		(4,677)		396,288
Increase (Decrease) in Stockholders' Equity
Net income												24,604
Other comprehensive (loss) income								339				339
Balance at end of period at Sep. 30, 2020		32,857		189,606		190,249		4,131		(17,672)		399,171
Balance at beginning of period at Jun. 30, 2020		32,857		189,526		185,163		2,868		(11,893)		398,521
Increase (Decrease) in Stockholders' Equity
Net income		0		0		8,402		0		0		8,402
Other comprehensive (loss) income		0		0		0		1,263		0		1,263
Cash dividends declared		0		0		(3,316)		0		0		(3,316)
Treasury stock purchased		0		0		0		0		(6,003)		(6,003)
Net issuance to employee stock plans, including related tax effects		0		(199)		0		0		224		25
Recognition of stock based compensation		0		279		0		0		0		279
Balance at end of period at Sep. 30, 2020		32,857		189,606		190,249		4,131		(17,672)		399,171
Balance at beginning of period (Accounting Standards Update 2016-13) at Dec. 31, 2020	$ 0		$ 0		$ (5,242)		$ 0		$ 0		$ (5,242)
Balance at beginning of period at Dec. 31, 2020		32,857		190,084		195,607		6,740		(18,223)		407,065
Increase (Decrease) in Stockholders' Equity
Net income		0		0		18,505		0		0		18,505
Other comprehensive (loss) income		0		0		0		(858)		0		(858)
Cash dividends declared		0		0		(6,876)		0		0		(6,876)
Net issuance to employee stock plans, including related tax effects		0		(280)		0		0		449		169
Recognition of stock based compensation		0		997		0		0		0		997
Balance at end of period at Jun. 30, 2021		32,857		190,801		201,994		5,882		(17,774)		413,760
Balance at beginning of period (Accounting Standards Update 2016-13) at Dec. 31, 2020	$ 0		$ 0		$ (5,242)		$ 0		$ 0		$ (5,242)
Balance at beginning of period at Dec. 31, 2020		32,857		190,084		195,607		6,740		(18,223)		407,065
Increase (Decrease) in Stockholders' Equity
Net income												29,533
Other comprehensive (loss) income								(3,852)				(3,852)
Balance at end of period at Sep. 30, 2021		32,857		190,892		209,426		2,888		(17,628)		418,435
Balance at beginning of period at Jun. 30, 2021		32,857		190,801		201,994		5,882		(17,774)		413,760
Increase (Decrease) in Stockholders' Equity
Net income		0		0		11,028		0		0		11,028
Other comprehensive (loss) income		0		0		0		(2,994)		0		(2,994)
Cash dividends declared		0		0		(3,596)		0		0		(3,596)
Net issuance to employee stock plans, including related tax effects		0		(276)		0		0		146		(130)
Recognition of stock based compensation		0		367		0		0		0		367
Balance at end of period at Sep. 30, 2021		$ 32,857		$ 190,892		$ 209,426		$ 2,888		$ (17,628)		$ 418,435