Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 4. Fair Value Measurements

Prior to the IPO, the Company’s convertible preferred stock warrant liability was measured on a recurring basis and was classified within Level III of the fair value hierarchy because some of the inputs used in its measurement were neither directly or indirectly observable. The valuation methodology and underlying assumptions in the fair value determination are discussed in Note 3, Basis of Presentation and Summary of Significant Accounting Policies, and Note 13, Convertible Preferred Stock Warrants and Common Stock Warrants.  

Immediately prior to the IPO, the convertible preferred stock warrant liability was remeasured to fair value, resulting in a loss of $3.7 million which was recorded in other expense, net. Upon the closing of the IPO, the entire balance of $5.7 million in convertible preferred stock warrant liability was reclassified to additional paid-in capital.

There were no transfers into or out of Level III during the year ended December 31, 2017. 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	$	—