CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Class A Common Stock [Member]	Class B Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2017	$ 179,465	$ 67	$ 9	$ 62,675	$ 151,608	$ (34,894)
Balance, shares at Dec. 31, 2017		6,694	898
Net income	1,529				1,529
Issuance of restricted stock	0
Issuance of restricted stock (in shares)		4	0
Dividends declared per common share	(1,784)	$ 0	$ 0	0	(1,784)	0
Compensation expense related to restricted stock awards	551	0	0	551	0	0
Purchase of shares held in treasury	(93)	0	0	0	0	(93)
401(k) plan contribution	253	0	0	(80)	0	333
Balance at Mar. 31, 2018	179,921	$ 67	$ 9	63,146	151,353	(34,654)
Balance, shares at Mar. 31, 2018		6,698	898
Balance at Dec. 31, 2017	179,465	$ 67	$ 9	62,675	151,608	(34,894)
Balance, shares at Dec. 31, 2017		6,694	898
Issuance of restricted stock (in shares)		27	37
Balance at Dec. 31, 2018	184,999	$ 67	$ 9	64,795	156,689	(36,561)
Balance, shares at Dec. 31, 2018		6,732	923
Net income	1,370				1,370
Issuance of restricted stock (in shares)		0	0
Dividends declared per common share	(1,784)	$ 0	$ 0	0	(1,784)	0
Compensation expense related to restricted stock awards	559	0	0	559	0	0
Purchase of shares held in treasury	(80)	0	0	0	0	(80)
401(k) plan contribution	262	0	0	(113)	0	375
Balance at Mar. 31, 2019	$ 185,326	$ 67	$ 9	$ 65,241	$ 156,275	$ (36,266)
Balance, shares at Mar. 31, 2019		6,732	923