Fair Value Measurements (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2019

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Option Pricing Model Assumptions

Additionally, the model’s inputs reflect assumptions that market participants would use in pricing the instrument in a current period transaction and included:

	December 31,
	2018
Time to liquidity (years)	0.57
Expected volatility	62.5%
Discounted cash flow rate	12.0%
Risk-free interest rate	2.6%
Marketability discount rate	14%

Additionally, the model’s inputs reflect assumptions that market participants would use in pricing the instrument in a current period transaction and included:

	Year Ended December 31,
	2017	2018
Time to liquidity (years)	1.75	0.57
Expected volatility	50.0%	62.5%
Discounted cash flow rate	18.0%	12.0%
Risk-free interest rate	1.9%	2.6%
Marketability discount rate	27%	14%

Financial Liabilities Measure on a Recurring Basis

The following table sets forth the fair value of the Company’s financial liabilities measured on a recurring basis, as of December 31, 2018 and March 31, 2019 (in thousands):

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Liabilities
Redeemable convertible warrant liability	$	—	$	—	$	16,091	$	16,091

	March 31, 2019
	Level 1		Level 2		Level 3		Total
Liabilities
Redeemable convertible warrant liability	$	—	$	—	$	31,803	$	31,803

The following table sets forth the fair value of the Company’s financial liabilities measured on a recurring basis, as of December 31, 2017 and 2018 (in thousands):

	December 31, 2017
	Level 1		Level 2		Level 3		Total
Liabilities
Redeemable convertible warrant liability	$	—	$	—	$	4,185	$	4,185

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Liabilities
Redeemable convertible warrant liability	$	—	$	—	$	16,091	$	16,091

Changes in the Redeemable Convertible Warrant Liability

The changes in the redeemable convertible warrant liability are summarized below (in thousands):

Fair Value at December 31, 2018	$	16,091
Change in fair value recorded in other income (expense), net	15,712
Fair Value at March 31, 2019	$	31,803

The changes in the redeemable convertible warrant liability are summarized below (in thousands):

Fair value at December 31, 2016	$	7,143
Change in fair value recorded in other income (expense), net	(2,958		)
Fair value at December 31, 2017	4,185
Change in fair value recorded in other income (expense), net	11,906
Fair value at December 31, 2018	$	16,091