UNAUDITED QUARTERLY DATA - Effect of Restatement on Previously Filed Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016
Current assets:
Cash and cash equivalents	$ 27,464		$ 83,964	$ 17,055	$ 15,360	$ 51,870	$ 12,745	$ 17,780	$ 18,034	$ 18,198
Accounts receivable	21,712		15,748	19,443	14,707	9,815	6,834	6,662	6,892	5,607
Finance receivables, net	6,260		4,603	2,234	3,296	1,441	9,743	2,149	1,442	3,349
Inventory, net	10,908		8,038	11,923	12,019	8,876	5,192	3,677	4,438	3,926
Prepaid expenses and other current assets	1,558	$ 1,180	929	1,278	1,610	1,056	879	1,594	1,677	1,352
Deferred income taxes								0	0	0	$ 2,300
Total current assets	67,902		113,282	51,933	46,992	73,058	35,393	31,862	32,483	32,432
Non-current assets:
Finance receivables due after one year, net	11,596		13,246	9,870	11,728	7,742	8,607	7,548	3,956	3,962
Other assets	2,099	1,974	720	414	458	289	319	231	144	163
Property and equipment, net	9,180		11,273	12,243	12,443	10,701	11,111	11,341	11,994	12,436
Deferred income taxes				0	0	0	0	0	0	0
Intangibles, net	26,171		29,325	30,119	30,910	578	622	666	711	754
Goodwill	64,149		64,149	64,149	64,403	11,492	11,492	11,492	11,492	11,703
Total non-current assets	113,195		118,713	116,795	119,942	30,802	32,151	31,278	28,297	29,018
Total assets	181,097		231,995	168,728	166,934	103,860	67,544	63,140	60,780	61,450
Current liabilities:
Accounts payable	27,511		30,468	29,574	23,908	14,506	16,345	11,819	9,109	8,710
Accrued expenses	23,258		19,291	18,508	16,623	12,217	11,873	8,792	7,541	8,135
Line of credit, net						7,051	7,036	7,034	7,091	7,271
Capital lease obligations and current obligations under long-term debt	12,497		34,639	4,470	5,488	2,628	3,198	3,785	4,331	4,952
Income taxes payable	254		0		0	0	10	23	21	15
Deferred revenue	1,539	1,638	511	511	730	439	268	310	478	94
Deferred gain from sale-leaseback transactions				0	0	0	0	0	0	0
Total current liabilities	65,059		84,909	53,063	46,749	36,841	38,730	31,763	28,571	29,177
Long-term liabilities:
Revolving credit facility				10,000	10,000
Deferred income taxes	71		67	96	91	109	94	78	63	47
Capital lease obligations and long-term debt, less current portion	276		1,127	22,895	24,570	1,049	1,061	1,239	1,394	1,517
Accrued expenses, less current portion	100		66	66	65	62	53	52	52	11
Deferred gain from sale-leaseback transactions, less current portion					0	0	0
Total long-term liabilities	447		1,260	33,057	34,726	1,220	1,208	1,369	1,509	1,575
Total liabilities	65,506		86,169	86,120	81,475	38,061	39,938	33,132	30,080	30,752
Commitments and contingencies
Temporary equity, preferred stock	3,138		3,138	3,138	3,138	3,138	3,138	3,138	3,138	3,138
Preferred stock	0		0	0	0	0	0	0	0	0
Common stock	376,853		375,436	310,522	310,150	286,296	245,999	245,463	245,230	244,996
Accumulated deficit	(264,400)	$ (232,372)	(232,748)	(231,052)	(227,829)	(223,635)	(221,531)	(218,593)	(217,668)	(217,436)
Total shareholders’ equity	112,453		142,688	79,470	82,321	62,661	24,468	26,870	27,562	27,560	19,328
Total liabilities, convertible preferred stock and shareholders’ equity	$ 181,097		$ 231,995	168,728	166,934	103,860	67,544	63,140	60,780	61,450
As Previously Reported
Current assets:
Cash and cash equivalents				17,107	15,386	51,870	12,745	17,780	18,034	18,198
Accounts receivable				23,166	15,472	10,288	7,193	6,734	6,796	5,840
Finance receivables, net				3,904	5,517	3,082	11,010	2,057	1,442	3,349
Inventory, net				11,030	11,215	8,240	4,586	4,147	4,786	4,264
Prepaid expenses and other current assets				1,869	1,971	1,122	968	1,628	1,764	1,439
Deferred income taxes								2,271	2,271	2,271
Total current assets				57,076	49,561	74,602	36,502	34,617	35,093	35,361
Non-current assets:
Finance receivables due after one year, net				9,679	11,215	7,742	8,607	7,548	3,956	3,962
Other assets				1,214	1,120	750	687	137	145	163
Property and equipment, net				12,198	12,622	11,850	12,111	9,173	9,433	9,570
Deferred income taxes				16,911	14,774	28,205	27,670	25,359	25,568	25,568
Intangibles, net				30,119	30,910	578	622	666	711	754
Goodwill				64,196	64,449	11,492	11,492	11,492	11,492	11,703
Total non-current assets				134,317	135,090	60,617	61,189	54,375	51,305	51,720
Total assets				191,393	184,651	135,219	97,691	88,992	86,398	87,081
Current liabilities:
Accounts payable				29,446	23,775	14,211	16,054	11,529	9,090	8,693
Accrued expenses				7,961	6,798	3,795	4,130	3,111	2,912	3,912
Line of credit, net						7,051	7,036	7,021	7,078	7,258
Capital lease obligations and current obligations under long-term debt				4,475	5,121	2,649	3,230	786	766	834
Income taxes payable					6	10	10	0	6	8
Deferred revenue				441	595	0	0	0	0	0
Deferred gain from sale-leaseback transactions				198	198	197	239	255	470	685
Total current liabilities				42,521	36,493	27,913	30,699	22,702	20,322	21,390
Long-term liabilities:
Revolving credit facility				10,000	10,000
Deferred income taxes				0	0	0	0	0	0	0
Capital lease obligations and long-term debt, less current portion				22,895	23,874	1,049	1,061	1,239	1,394	1,517
Accrued expenses, less current portion				66	65	62	53	52	52	11
Deferred gain from sale-leaseback transactions, less current portion					49	99	100
Total long-term liabilities				32,961	33,988	1,210	1,214	1,291	1,446	1,528
Total liabilities				75,482	70,481	29,123	31,913	23,993	21,768	22,918
Commitments and contingencies
Temporary equity, preferred stock				0	0	0	0	0	0	0
Preferred stock				0	0	0	0	0	0	0
Common stock				307,634	307,053	286,463	245,999	245,463	245,230	244,996
Accumulated deficit				(194,861)	(196,021)	(183,505)	(183,359)	(183,602)	(183,738)	(183,971)
Total shareholders’ equity				115,911	114,170	106,096	65,778	64,999	64,630	64,163
Total liabilities, convertible preferred stock and shareholders’ equity				191,393	184,651	135,219	97,691	88,992	86,398	87,081
Adjustments
Current assets:
Cash and cash equivalents				(52)	(26)	0	0	0	0	0
Accounts receivable				(3,723)	(765)	(473)	(359)	(72)	96	(233)
Finance receivables, net				(1,670)	(2,221)	(1,641)	(1,267)	92	0	0
Inventory, net				893	804	636	606	(470)	(348)	(338)
Prepaid expenses and other current assets				(591)	(361)	(66)	(89)	(34)	(87)	(87)
Deferred income taxes								(2,271)	(2,271)	(2,271)
Total current assets				(5,143)	(2,569)	(1,544)	(1,109)	(2,755)	(2,610)	(2,929)
Non-current assets:
Finance receivables due after one year, net				191	513	0	0	0	0	0
Other assets				(800)	(662)	(461)	(368)	94	(1)	0
Property and equipment, net				45	(179)	(1,149)	(1,000)	2,168	2,561	2,866
Deferred income taxes				(16,911)	(14,774)	(28,205)	(27,670)	(25,359)	(25,568)	(25,568)
Intangibles, net				0	0	0	0	0	0	0
Goodwill				(47)	(46)	0	0	0	0	0
Total non-current assets				(17,522)	(15,148)	(29,815)	(29,038)	(23,097)	(23,008)	(22,702)
Total assets				(22,665)	(17,717)	(31,359)	(30,147)	(25,852)	(25,618)	(25,631)
Current liabilities:
Accounts payable				128	133	295	291	290	19	17
Accrued expenses				10,547	9,825	8,422	7,743	5,681	4,629	4,223
Line of credit, net						0	0	13	13	13
Capital lease obligations and current obligations under long-term debt				(5)	367	(21)	(32)	2,999	3,565	4,118
Income taxes payable					(6)	(10)	0	23	15	7
Deferred revenue				70	135	439	268	310	478	94
Deferred gain from sale-leaseback transactions				(198)	(198)	(197)	(239)	(255)	(470)	(685)
Total current liabilities				10,542	10,256	8,928	8,031	9,061	8,249	7,787
Long-term liabilities:
Revolving credit facility				0	0
Deferred income taxes				96	91	109	94	78	63	47
Capital lease obligations and long-term debt, less current portion				0	696	0	0	0	0	0
Accrued expenses, less current portion				0	0	0	0	0	0	0
Deferred gain from sale-leaseback transactions, less current portion					(49)	(99)	(100)
Total long-term liabilities				96	738	10	(6)	78	63	47
Total liabilities				10,638	10,994	8,938	8,025	9,139	8,312	7,834
Commitments and contingencies
Temporary equity, preferred stock				3,138	3,138	3,138	3,138	3,138	3,138	3,138
Preferred stock				0	0	0	0	0	0	0
Common stock				2,888	3,097	(167)	0	0	0	0
Accumulated deficit				(36,191)	(31,808)	(40,130)	(38,172)	(34,991)	(33,930)	(33,465)	$ (32,600)
Total shareholders’ equity				(36,441)	(31,849)	(43,435)	(41,310)	(38,129)	(37,068)	(36,603)
Total liabilities, convertible preferred stock and shareholders’ equity				(22,665)	(17,717)	(31,359)	(30,147)	(25,852)	(25,618)	(25,631)
Series A Convertible Preferred Stock
Long-term liabilities:
Preferred stock				0	0	0	0	0	0	0
Series A Convertible Preferred Stock | As Previously Reported
Long-term liabilities:
Preferred stock				3,138	3,138	3,138	3,138	3,138	3,138	3,138
Series A Convertible Preferred Stock | Adjustments
Long-term liabilities:
Preferred stock				$ (3,138)	$ (3,138)	$ (3,138)	$ (3,138)	$ (3,138)	$ (3,138)	$ (3,138)