CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Maximum Cash Obligation Related To ESOP Shares [Member]
Beginning Balance at Dec. 31, 2018	$ 334,882	$ 52,122	$ 371,848	$ (3,250)	$ (36,968)	$ (48,870)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 84,164 and 91,274 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	5,134	2,932			2,202
Issuance 1,929, and 1,712 shares of common stock under the employee stock purchase plan for 3 months ended March 31, 2019 and 2020, respectively	105	105
Unearned restricted stock compensation	170	170
Forfeiture of 703 and 443 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	(34)	(34)
Change related to ESOP shares	(981)					(981)
Net income	11,203		11,203
Cash dividends ($0.82 and $0.89 per share for 3 months ended March 31, 2019 and 2020, respectively)	(7,657)		(7,657)
Purchase of 69,771 and 68,881 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	(4,291)				(4,291)
Other comprehensive income	2,249			2,249
Ending Balance at Mar. 31, 2019	340,780	55,295	375,394	(1,001)	(39,057)	(49,851)
Beginning Balance at Dec. 31, 2019	375,211	55,943	409,509	1,415	(39,830)	(51,826)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 84,164 and 91,274 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	5,933	3,504			2,429
Issuance 1,929, and 1,712 shares of common stock under the employee stock purchase plan for 3 months ended March 31, 2019 and 2020, respectively	101	101
Unearned restricted stock compensation	202	202
Forfeiture of 703 and 443 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	(23)	(23)
Share-based compensation	6	6
Change related to ESOP shares	1,577					1,577
Net income	7,075		7,075
Cash dividends ($0.82 and $0.89 per share for 3 months ended March 31, 2019 and 2020, respectively)	(8,324)		(8,324)
Purchase of 69,771 and 68,881 shares of common stock for 3 months ended March 31, 2019 and 2020, respectively	(4,538)				(4,538)
Other comprehensive income	(409)			(409)
Ending Balance at Mar. 31, 2020	$ 376,811	$ 59,733	$ 408,260	$ 1,006	$ (41,939)	$ (50,249)