Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net revenue	$ 9,127,057	$ 6,779,174	$ 4,720,895
Cost of goods sold	6,979,725	5,192,451	3,602,072
Gross profit	2,147,332	1,586,723	1,118,823
Operating expenses:
Customer service and merchant fees	356,727	260,046	169,516
Advertising	1,095,840	774,189	549,959
Selling, operations, technology, general and administrative	1,624,706	1,025,767	634,801
Total operating expenses	3,077,273	2,060,002	1,354,276
Loss from operations	(929,941)	(473,279)	(235,453)
Interest (expense), net	(54,514)	(28,560)	(9,433)
Other income (expense), net	2,881	(204)	758
Loss before income taxes	(981,574)	(502,043)	(244,128)
Provision for income taxes, net	3,010	2,037	486
Net loss	$ (984,584)	$ (504,080)	$ (244,614)
Net loss per share, basic and diluted (in dollars per share)	$ (10.68)	$ (5.63)	$ (2.81)
Weighted average number of common stock outstanding used in computing per share amounts, basic and diluted (in shares)	92,200	89,472	86,983