INCOME TAXES - Deferred income tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Deferred tax assets:
Accruals and advances	$ 8,586		$ 7,748
Stock-based compensation	3,750		0
Bond hedge	0		3,019
Accruals for chargebacks and returns	7,603		7,132
Inventory	4,720		1,228
Intangible asset	14,923		9,393
Net operating loss carryforwards	4,767		5,604
Other	1,459		4,682
Total deferred tax assets	45,808		38,806
Deferred tax liabilities:
Depreciation	(6,029)		(4,437)
Debt discount	0		(1,316)
Intangible assets	(13)		(11)
Other	(1,008)		(2,813)
Total deferred tax liabilities	(7,050)		(8,577)
Valuation allowance	(432)	$ (100)	(2,265)
Deferred tax assets, net of deferred tax liabilities and valuation allowance	$ 38,326		$ 27,964