Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in-Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Series Seed Convertible Preferred Stock	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock
Beginning balance at Dec. 31, 2017	$ (6,862)		$ 32	$ (6,894)
Temporary equity, beginning balance, shares at Dec. 31, 2017						0		0
Temporary equity, beginning balance at Dec. 31, 2017						$ 0		$ 0
Beginning balance, shares at Dec. 31, 2017		9,160,888
Issuance of Series A preferred stock for cash, net of $0.4 million in offering costs							$ 71,944
Issuance of Series A preferred stock for cash, net of $0.4 million in offering costs, shares							41,328,286
Temporary equity, issuance of stock for acquisition						$ 29,200
Temporary equity, issuance of stock for acquisition, shares						20,000,000
Issuance of stock for acquisition	2,874		2,874
Issuance of stock for acquisition. shares		1,101,278
Issuance of Series A preferred stock to convert debt and accrued interest							$ 6,124
Issuance of Series A preferred stock to convert debt and accrued interest, shares							3,499,209
Stock-based compensation	605		605
Incremental vesting conditions place on previously issued common shares		(4,580,444)
Net loss	(26,037)			(26,037)
Ending balance at Mar. 31, 2018	(29,420)		3,511	(32,931)
Temporary equity, ending balance, shares at Mar. 31, 2018						20,000,000	44,827,495
Temporary equity, ending balance at Mar. 31, 2018						$ 29,200	$ 78,068
Ending balance, shares at Mar. 31, 2018		5,681,722
Beginning balance at Dec. 31, 2018	(120,069)	$ 2	33,853	(153,863)	$ (61)
Temporary equity, beginning balance, shares at Dec. 31, 2018						20,000,000	45,714,286	71,506,513
Temporary equity, beginning balance at Dec. 31, 2018						$ 29,200	$ 79,615	$ 229,552
Beginning balance, shares at Dec. 31, 2018		8,051,418
Issuance of common stock in connection with a public offering, net of underwriting discounts, commissions, and offering costs	291,344	$ 2	291,342
Issuance of common stock in connection with a public offering, net of underwriting discounts, commissions, and offering costs, shares		19,837,500
Conversion of convertible preferred stock into common stock	338,367	$ 3	338,364
Convertible preferred stock, conversion of convertible preferred stock into common stock, shares						(20,000,000)	(45,714,286)	(71,506,513)
Convertible preferred stock, conversion of convertible preferred stock into common stock						$ (29,200)	$ (79,615)	$ (229,552)
Conversion of convertible preferred stock into common stock, shares		30,493,460
Vesting of restricted stock, shares		1,619,592
Stock-based compensation	3,089		3,089
Stock-based compensation, shares		27,500
Net loss	(32,611)			(32,611)
Other comprehensive income	140				140
Ending balance at Mar. 31, 2019	$ 480,260	$ 7	$ 666,648	$ (186,474)	$ 79
Temporary equity, ending balance, shares at Mar. 31, 2019						0	0	0
Ending balance, shares at Mar. 31, 2019		60,029,470