CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total
Balances at Dec. 31, 2018	$ 127	$ 65,434	$ 120,574	$ (2,950)	$ 183,185
Net income			3,754		3,754
Other comprehensive income (loss)				1,446	1,446
Stock-based compensation		63			63
Exercise of options and vesting of restricted stock, net of shares surrendered	1	(89)			(88)
Cash dividends declared			(1,278)		(1,278)
Balances at Mar. 31, 2019	128	65,408	123,050	(1,504)	187,082
Balances at Dec. 31, 2018	127	65,434	120,574	(2,950)	183,185
Net income					16,198
Balances at Dec. 31, 2019	125	61,045	131,425	207	192,802
Balances at Mar. 31, 2019	128	65,408	123,050	(1,504)	187,082
Net income			4,224		4,224
Other comprehensive income (loss)				1,311	1,311
Stock-based compensation		(32)			(32)
Cash dividends declared			(1,278)		(1,278)
Balances at Jun. 30, 2019	128	65,376	125,996	(193)	191,307
Net income			4,206		4,206
Other comprehensive income (loss)				226	226
Retirement of common stock	(1)	(558)			(559)
Stock-based compensation		61			61
Cash dividends declared			(1,278)		(1,278)
Balances at Sep. 30, 2019	127	64,879	128,924	33	193,963
Net income			4,014		4,014
Other comprehensive income (loss)				174	174
Retirement of common stock	(2)	(3,891)			(3,893)
Stock-based compensation		57			57
Cash dividends declared			(1,513)		(1,513)
Balances at Dec. 31, 2019	125	61,045	131,425	207	192,802
Cumulative effect adjustment (ASU 2016-01)					131,425
Net income			3,118		3,118
Other comprehensive income (loss)				1,251	1,251
Stock-based compensation		61			61
Vesting of restricted stock, net of shares surrendered		(39)			(39)
Cash dividends declared			(1,499)		(1,499)
Balances at Mar. 31, 2020	125	61,067	133,044	1,458	195,694
Balances at Dec. 31, 2019	125	61,045	131,425	207	192,802
Net income					15,730
Balances at Dec. 31, 2020	118	52,167	141,205	1,529	195,019
Balances at Mar. 31, 2020	125	61,067	133,044	1,458	195,694
Net income			5,335		5,335
Other comprehensive income (loss)				546	546
Stock-based compensation		62			62
Cash dividends declared			(1,503)		(1,503)
Balances at Jun. 30, 2020	125	61,129	136,876	2,004	200,134
Net income			3,391		3,391
Other comprehensive income (loss)				(100)	(100)
Retirement of common stock	(3)	(3,106)			(3,109)
Stock-based compensation		67			67
Cash dividends declared			(1,502)		(1,502)
Balances at Sep. 30, 2020	122	58,090	138,765	1,904	198,881
Net income			3,886		3,886
Other comprehensive income (loss)				(375)	(375)
Retirement of common stock	(4)	(5,999)			(6,003)
Stock-based compensation		73			73
Cash dividends declared			(1,446)		(1,446)
Exercise of options		3			3
Balances at Dec. 31, 2020	$ 118	$ 52,167	$ 141,205	$ 1,529	195,019
Cumulative effect adjustment (ASU 2016-01)					$ 141,205