BUSINESS SEGMENTS (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended				12 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Segment reporting information
Revenue, net		$ 440,580		$ 424,007		$ 1,369,044		$ 1,288,466
Cost of goods sold		353,864		340,332		1,096,716		1,033,713
Gross profit		86,716		83,675		272,328		254,753
Operating expenses		134,548		95,550		441,090		278,672
Other income (expense), net	[1]	(1,566)		5,358		(1,312)		1,062
Pre-tax income (loss)		(49,398)		(6,517)		(170,074)		(22,857)
Provision for income taxes		(141)		(5,412)		(445)		(7,727)
Consolidated net loss		(49,257)	[2]	(1,105)	[2]	(169,629)	[2]	(15,130)	[2]	$ (266,421)	$ (12,369)
Direct
Segment reporting information
Revenue, net		15,424		19,645		46,409		64,572
Cost of goods sold	[3]	16,205		19,577		45,649		61,687
Gross profit		(781)		68		760		2,885
Partner
Segment reporting information
Revenue, net		420,351		400,419		1,307,045		1,211,536
Cost of goods sold		334,446		318,121		1,039,834		963,310
Gross profit		85,905		82,298		267,211		248,226
Retail Total
Segment reporting information
Revenue, net		435,775		420,064		1,353,454		1,276,108
Cost of goods sold		350,651		337,698		1,085,483		1,024,997
Gross profit		85,124		82,366		267,971		251,111
Operating expenses		124,571		90,592		399,540		264,455
Other income (expense), net	[1]	(515)		5,375		654		5,490
Pre-tax income (loss)		(39,962)		(2,851)		(130,915)		(7,854)
Provision for income taxes		(155)		(3,993)		(283)		(3,280)
Consolidated net loss	[2]	(39,807)		1,142		(130,632)		(4,574)
Other
Segment reporting information
Revenue, net		4,805		3,943		15,590		12,358
Cost of goods sold		3,213		2,634		11,233		8,716
Gross profit		1,592		1,309		4,357		3,642
Operating expenses		9,977		4,958		41,550		14,217
Other income (expense), net	[1]	(1,051)		(17)		(1,966)		(4,428)
Pre-tax income (loss)		(9,436)		(3,666)		(39,159)		(15,003)
Provision for income taxes		14		(1,419)		(162)		(4,447)
Consolidated net loss	[2]	(9,450)		(2,247)		(38,997)		(10,556)
Inter-segment sales or transfers
Segment reporting information
Other income (expense), net		$ 539		$ 403		$ 3,000		$ 1,100

[1] Excludes intercompany transactions eliminated in consolidation, which consist primarily of service fees and interest. The net amounts of these intercompany transactions were $539,000 and $403,000 for the three months ended September 30, 2018 and 2017, respectively, and $3.0 million and $1.1 million for the nine months ended September 30, 2018 and 2017, respectively.

[2] Net income (loss) presented for segment reporting purposes is before any adjustments attributable to noncontrolling interests.

[3] (1) Includes stock-based compensation as follows (Note 9): Cost of goods sold — direct$41 $46 $152 $134 Sales and marketing277 109 1,465 318 Technology583 166 1,725 476 General and administrative1,345 703 8,312 2,081 Total$2,246 $1,024 $11,654 $3,009