CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY (unaudited) - USD ($) $ in Thousands	Class B Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI (Loss), Net	Total
Balance at Dec. 31, 2017	$ 3	$ 81	$ 211,145	$ 25,861	$ (206)	$ 236,884
Balance (in shares) at Dec. 31, 2017		8,196,310				272,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock, net of forfeiture			440			$ 440
Restricted stock, net of forfeiture (in shares)		8,987
Issuance of common stock, net			(33)			(33)
Issuance of shares for exercise of stock options and tax withholding for restricted stock vesting (in shares)		1,937
Issuance of shares for exercise of stock options and tax withholding for restricted stock vesting			12			12
Employee and non-employee stock-based compensation			1,219			1,219
Net income				19,268		19,268
Other comprehensive income (loss)					(497)	(497)
Balance at Sep. 30, 2018	$ 3	$ 81	212,759	45,129	(703)	$ 257,269
Balance (in shares) at Sep. 30, 2018	272,636	8,207,234				272,636
Balance at Jun. 30, 2018	$ 3	$ 81	212,100	38,016	(617)	$ 249,583
Balance (in shares) at Jun. 30, 2018	272,636	8,205,234
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of shares for tax withholding for restricted stock vesting			60			60
Redemption of shares for tax withholding for restricted stock vesting (in shares)		2,000
Employee and non-employee stock-based compensation			599			599
Net income				7,113		7,113
Other comprehensive income (loss)					(86)	(86)
Balance at Sep. 30, 2018	$ 3	$ 81	212,759	45,129	(703)	$ 257,269
Balance (in shares) at Sep. 30, 2018	272,636	8,207,234				272,636
Balance at Dec. 31, 2018	$ 3	$ 82	213,490	51,415	(473)	$ 264,517
Balance (in shares) at Dec. 31, 2018		8,217,274				272,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of shares for tax withholding for restricted stock vesting			88			$ 88
Redemption of shares for tax withholding for restricted stock vesting (in shares)		(2,881)
Restricted stock, net of forfeiture			(1)			(1)
Restricted stock, net of forfeiture (in shares)		105,459
Employee and non-employee stock-based compensation			2,276			2,276
Net income				22,271		22,271
Cumulative effect of adopting new accounting standard | ASU 2016-01				(68)	68
Cumulative effect of adopting new accounting standard | ASU 2014-09				(117)		(117)
Other comprehensive income (loss)					2,144	2,144
Balance at Sep. 30, 2019	$ 3	$ 82	215,677	73,501	1,739	$ 291,002
Balance (in shares) at Sep. 30, 2019	272,636	8,319,852				272,636
Balance at Jun. 30, 2019	$ 3	$ 82	214,880	65,818	547	$ 281,330
Balance (in shares) at Jun. 30, 2019	272,636	8,320,816
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock forfeited (in shares)		(964)
Restricted stock forfeited			(1)			(1)
Employee and non-employee stock-based compensation			798			798
Net income				7,683		7,683
Other comprehensive income (loss)					1,192	1,192
Balance at Sep. 30, 2019	$ 3	$ 82	$ 215,677	$ 73,501	$ 1,739	$ 291,002
Balance (in shares) at Sep. 30, 2019	272,636	8,319,852				272,636