CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Traditional Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ 100,440	$ 73	$ 243,598	$ 232	$ (143,463)
Beginning balance (in shares) at Dec. 31, 2017		7,303,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after equity in losses of unconsolidated affiliates	2,383
Ending balance at Sep. 30, 2018	111,601	$ 76	249,755	216	(138,446)
Ending balance (in shares) at Sep. 30, 2018		7,553,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of accounting standards	2,634				2,634
Beginning balance at Jan. 01, 2018	103,074	$ 73	243,598	232	(140,829)
Beginning balance (in shares) at Jan. 01, 2018		7,303,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after equity in losses of unconsolidated affiliates	2,383				2,383
Issuance of common stock, net of shares withheld for employee taxes	2,386	$ 3	2,383
Issuance of common stock, net of shares withheld for employee taxes (in shares)		250,000
Stock-based compensation	3,774		3,774
Other comprehensive income (loss)	(16)			(16)
Ending balance at Jun. 30, 2018	109,922	$ 75	246,422	201	(136,776)
Ending balance (in shares) at Jun. 30, 2018		7,498,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after equity in losses of unconsolidated affiliates	(1,670)				(1,670)
Issuance of common stock, net of shares withheld for employee taxes	1,928	$ 1	1,927
Issuance of common stock, net of shares withheld for employee taxes (in shares)		55,000
Stock-based compensation	1,406		1,406
Other comprehensive income (loss)	15			15
Ending balance at Sep. 30, 2018	111,601	$ 76	249,755	216	(138,446)
Ending balance (in shares) at Sep. 30, 2018		7,553,000
Beginning balance at Dec. 31, 2018	122,409	$ 77	257,034	277	(134,979)
Beginning balance (in shares) at Dec. 31, 2018		7,676,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after equity in losses of unconsolidated affiliates	263				263
Issuance of common stock, net of shares withheld for employee taxes	(2,247)	$ 1	(2,248)
Issuance of common stock, net of shares withheld for employee taxes (in shares)		148,000
Stock-based compensation	3,625		3,625
Convertible notes, equity	29,770		29,770
Other comprehensive income (loss)	(137)			(137)
Ending balance at Sep. 30, 2019	153,683	$ 78	288,181	140	(134,716)
Ending balance (in shares) at Sep. 30, 2019		7,824,000
Beginning balance at Jun. 30, 2019	122,922	$ 78	256,952	298	(134,406)
Beginning balance (in shares) at Jun. 30, 2019		7,794,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income after equity in losses of unconsolidated affiliates	(310)				(310)
Issuance of common stock, net of shares withheld for employee taxes	213	$ 0	213
Issuance of common stock, net of shares withheld for employee taxes (in shares)		30,000
Stock-based compensation	1,246		1,246
Convertible notes, equity	29,770		29,770
Other comprehensive income (loss)	(158)			(158)
Ending balance at Sep. 30, 2019	$ 153,683	$ 78	$ 288,181	$ 140	$ (134,716)
Ending balance (in shares) at Sep. 30, 2019		7,824,000