CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - 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, 2016	$ 289,270	$ 44,606	$ 319,982	$ (3,359)	$ (31,178)	$ (40,781)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 114,935, 113,373 and 101,912 shares of common stock for the years ending 2017, 2018, and 2019, respectively	5,446	4,851	0	0	595	0
Issuance of 6,892, 8,172 and 7,720 shares of common stock under the employee stock purchase plan for the years ending 2017, 2018, and 2019, respectively	325	325	0	0	0	0
Unearned restricted stock compensation	(707)	(707)	0	0	0	0
Forfeiture of 3,934, 3,296 and 5,255 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(156)	(156)	0	0	0	0
Share-based compensation	11	11	0	0	0	0
Change related to ESOP shares	(2,527)	0	0	0	0	(2,527)
Net income	28,061	0	28,061	0	0	0
Cash dividends ($0.70, $0.75, and $0.82 per share) for the years ending 2017, 2018, and 2019, respectively	(6,485)	0	(6,485)	0	0	0
Purchase of 46,966, 116,962 and 89,124 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(2,435)	0	0	0	(2,435)	0
Other comprehensive income (loss)	913	0	0	913	0	0
Ending Balance at Dec. 31, 2017	311,716	48,930	341,558	(2,446)	(33,018)	(43,308)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 114,935, 113,373 and 101,912 shares of common stock for the years ending 2017, 2018, and 2019, respectively	6,220	3,386	0	0	2,834	0
Issuance of 6,892, 8,172 and 7,720 shares of common stock under the employee stock purchase plan for the years ending 2017, 2018, and 2019, respectively	421	421	0	0	0	0
Unearned restricted stock compensation	(463)	(463)	0	0	0	0
Forfeiture of 3,934, 3,296 and 5,255 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(152)	(152)	0	0	0	0
Change related to ESOP shares	(5,562)	0	0	0	0	(5,562)
Net income	36,767	0	36,767	0	0	0
Cash dividends ($0.70, $0.75, and $0.82 per share) for the years ending 2017, 2018, and 2019, respectively	(7,003)	0	(7,003)	0	0	0
Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Tax Effect			526	(526)
Purchase of 46,966, 116,962 and 89,124 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(6,784)	0	0	0	(6,784)	0
Other comprehensive income (loss)	(278)	0	0	(278)	0	0
Ending 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 114,935, 113,373 and 101,912 shares of common stock for the years ending 2017, 2018, and 2019, respectively	6,221	3,549	0	0	2,672	0
Issuance of 6,892, 8,172 and 7,720 shares of common stock under the employee stock purchase plan for the years ending 2017, 2018, and 2019, respectively	434	434	0	0	0	0
Unearned restricted stock compensation	86	86	0	0	0	0
Forfeiture of 3,934, 3,296 and 5,255 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(262)	(262)	0	0	0	0
Share-based compensation	14	14	0	0	0	0
Change related to ESOP shares	(2,956)	0	0	0	0	(2,956)
Net income	45,318	0	45,318	0	0	0
Cash dividends ($0.70, $0.75, and $0.82 per share) for the years ending 2017, 2018, and 2019, respectively	(7,657)	0	(7,657)	0	0	0
Purchase of 46,966, 116,962 and 89,124 shares of common stock for the years ending 2017, 2018, and 2019, respectively	(5,534)	0	0	0	(5,534)	0
Other comprehensive income (loss)	4,665	0	0	4,665	0	0
Ending Balance at Dec. 31, 2019	$ 375,211	$ 55,943	$ 409,509	$ 1,415	$ (39,830)	$ (51,826)