Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Deficit	Accum. Other Comp. Loss	Total CVG Stockholders’ Equity	Non- Controlling Interest
Beginning Balance (in shares) at Dec. 31, 2014		29,148,504
Beginning balance at Dec. 31, 2014	$ 58,836	$ 296	$ (6,622)	$ 231,907	$ (129,492)	$ (37,288)	$ 58,801	$ 35
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)		400,195
Issuance of restricted stock	4	$ 4					4
Surrender of common stock by employees (in shares)		(99,920)
Surrender of common stock by employees	(423)	$ (6)	(417)				(423)
Share-based compensation expense	2,853			2,853			2,853
Total comprehensive (loss) income	4,695				7,061	(2,366)	4,695	(35)
Total comprehensive (loss) income, including deconsolidation of noncontrolling interest	4,660
Ending balance (in shares) at Dec. 31, 2015		29,448,779
Ending balance at Dec. 31, 2015	65,930	$ 294	(7,039)	234,760	(122,431)	(39,654)	65,930	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)		557,584
Issuance of restricted stock	5	$ 5					5
Surrender of common stock by employees (in shares)		(135,009)
Surrender of common stock by employees	(714)		(714)				(714)
Share-based compensation expense	2,607			2,607			2,607
Recognition of excess tax benefits on share-based compensation expense	2,268				2,268		2,268
Total comprehensive (loss) income	$ (2,406)				6,785	(9,191)	(2,406)
Ending balance (in shares) at Dec. 31, 2016	29,871,354	29,871,354
Ending balance at Dec. 31, 2016	$ 67,690	$ 299	(7,753)	237,367	(113,378)	(48,845)	67,690	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)		509,306
Issuance of restricted stock	5	$ 5					5
Surrender of common stock by employees (in shares)		(161,382)
Surrender of common stock by employees	(1,361)		(1,361)				(1,361)
Share-based compensation expense	2,503			2,503			2,503
Total comprehensive (loss) income	$ 5,905				(1,705)	7,610	5,905
Ending balance (in shares) at Dec. 31, 2017	30,219,278	30,219,278
Ending balance at Dec. 31, 2017	$ 74,742	$ 304	$ (9,114)	$ 239,870	$ (115,083)	$ (41,235)	$ 74,742	$ 0