Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2017	$ 171	$ 24	$ 137,242	$ 293	$ 157,471	$ 295,201
Net (loss) income					4,417	4,417
Other comprehensive income (loss)				671		671
Stock-based employee compensation expense			826			826
Issuance of restricted shares, net			(18)			(18)
Effect of adoption of ASU 2014-09					591	591
Balance at Mar. 31, 2018	171	24	138,050	964	162,479	301,688
Balance at Dec. 31, 2017	171	24	137,242	293	157,471	295,201
Net (loss) income						26,002
Other comprehensive income (loss)						1,194
Balance at Sep. 30, 2018	171	24	140,404	1,487	184,064	326,150
Balance at Mar. 31, 2018	171	24	138,050	964	162,479	301,688
Net (loss) income					9,971	9,971
Other comprehensive income (loss)				580		580
Issuance of restricted shares, net			375			375
Stock-based employee compensation expense reversal			937			937
Balance at Jun. 30, 2018	171	24	139,362	1,544	172,450	313,551
Net (loss) income					11,614	11,614
Other comprehensive income (loss)				(57)		(57)
Issuance of restricted shares, net			(63)			(63)
Stock-based employee compensation expense reversal			1,105			1,105
Balance at Sep. 30, 2018	171	24	140,404	1,487	184,064	326,150
Balance at Dec. 31, 2018	171	24	142,177	204	200,566	343,142
Net (loss) income					4,433	4,433
Other comprehensive income (loss)				(432)		(432)
Stock-based employee compensation expense			1,262			1,262
Issuance of restricted shares, net	1		(669)			(668)
Balance at Mar. 31, 2019	172	24	142,770	(228)	204,999	347,737
Balance at Dec. 31, 2018	171	24	142,177	204	200,566	343,142
Net (loss) income						7,315
Other comprehensive income (loss)						(1,687)
Balance at Sep. 30, 2019	172	24	141,840	(1,483)	207,881	348,434
Balance at Mar. 31, 2019	172	24	142,770	(228)	204,999	347,737
Net (loss) income					6,071	6,071
Other comprehensive income (loss)				(690)		(690)
Issuance of restricted shares, net
Stock-based employee compensation expense reversal			(1,433)			(1,433)
Balance at Jun. 30, 2019	172	24	141,337	(918)	211,070	351,685
Net (loss) income					(3,189)	(3,189)
Other comprehensive income (loss)				(565)		(565)
Stock-based employee compensation expense			597			597
Issuance of restricted shares, net			(94)			(94)
Balance at Sep. 30, 2019	$ 172	$ 24	$ 141,840	$ (1,483)	$ 207,881	$ 348,434