Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability

The changes in the fair value of the convertible preferred stock warrant liability are summarized below (in thousands):

	Fair Value Measurements at Reporting Date Using Level III Inputs
Fair value at December 31, 2014	$	1,204
Issuance of convertible preferred stock warrants		147
Change in fair value recorded in other expense,    net		—
Fair value at December 31, 2015	$	1,351
Change in fair value recorded in other expense,    net		524
Fair value at December 31, 2016	$	1,875
Issuance of convertible preferred stock warrants		111
Change in fair value recorded in other expense,    net		3,725
Reclassification of unexercised warrant into    additional paid-in capital upon the IPO		(5,711	)
Fair value at December 31, 2017	$	—