Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Stockholders' Equity [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2014	$ 150,426	$ 148,084	$ 164	$ 143,475	$ 4,445	$ 2,342
Beginning balance, shares at Dec. 31, 2014			16,448,750
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	21,378	21,688			21,688	(310)
Noncontrolling interest contribution	1,301					1,301
Noncontrolling interest distribution	(2,411)					(2,411)
Stock-based compensation expense	3,884	3,884		3,884
Shares Paid for Tax Withholding for Share Based Compensation			(17,590)
Shares net settled with the Company to satisfy minimum employee personal income tax liabilities resulting from share based compensation plans	(248)	(248)		(248)
Excess tax benefits (provision) from stock-based compensation	97	97		97
Shares issued through stock plans	17	17	$ 1	16
Shares issued through stock plans, shares			86,970
Issuance of common stock, net of issuance costs	47,253	47,253	$ 40	47,213
Issuance of common stock, net of issuance costs, shares			4,025,000
Ending balance at Dec. 31, 2015	221,697	220,775	$ 205	194,437	26,133	922
Ending balance, shares at Dec. 31, 2015			20,543,130
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	20,926	21,022			21,022	(96)
Noncontrolling interest distribution	(725)					(725)
Stock-based compensation expense	3,471	3,471		3,471
Shares Paid for Tax Withholding for Share Based Compensation			(62,597)
Shares net settled with the Company to satisfy minimum employee personal income tax liabilities resulting from share based compensation plans	(648)	(648)		(648)
Excess tax benefits (provision) from stock-based compensation	(97)	(97)		(97)
Shares issued through stock plans	0		$ 2	(2)
Shares issued through stock plans, shares			231,633
Ending balance at Dec. 31, 2016	244,624	244,523	$ 207	197,161	47,155	101
Ending balance, shares at Dec. 31, 2016			20,712,166
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	17,141	17,152			17,152	(11)
Stock-based compensation expense	2,803	2,803		2,803
Shares Paid for Tax Withholding for Share Based Compensation			(56,092)
Shares net settled with the Company to satisfy minimum employee personal income tax liabilities resulting from share based compensation plans	(590)	(590)		(590)
Shares issued through stock plans	102	102	$ 2	100
Shares issued through stock plans, shares			220,763
Ending balance at Dec. 31, 2017	$ 264,080	$ 263,990	$ 209	$ 199,474	$ 64,307	$ 90
Ending balance, shares at Dec. 31, 2017			20,876,837