Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Offering costs incurred	$ 365
Unrealized gain (loss) on investments, tax	$ 156	$ 0	$ 0