Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table sets forth a summary of changes in the fair value of level 3 liabilities measured at fair value on a recurring basis for the three months ended March 31, 2018:

Description	Balance at December 31, 2017		Change in Fair Value			Balance at March 31, 2018
Warrant liability	$	8,453	$	(8,166	)	$	287