Stockholders' Equity (Deficit) - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Oct. 01, 2018	Dec. 31, 2018	Dec. 31, 2017
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of common stock		$ 78,806	$ 10,430
Consulting services		$ 13,887	$ 12,002
Preferred stock, shares outstanding		0	0
Selling, General and Administrative Expenses [Member]
Subsidiary Sale Of Stock [Line Items]
Consulting services		$ 11,936	$ 8,744
Common Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Common stock issued, Shares		4,801,000	421,000
Common stock issued for services, Shares			4,000
Common Stock [Member] | Selling, General and Administrative Expenses [Member]
Subsidiary Sale Of Stock [Line Items]
Consulting services			$ 100
Private Placement [Member]
Subsidiary Sale Of Stock [Line Items]
Common stock issued, Shares		316,080	421,450
Proceeds from issuance of common stock		$ 7,900	$ 10,400
IPO [Member]
Subsidiary Sale Of Stock [Line Items]
Common stock issued, Shares	4,485,000
Proceeds from issuance of common stock	$ 67,300