Derivative warrant liabilities (Tables)

12 Months Ended

Dec. 31, 2017



	December 28, 2016 Warrants				February 14, 2014 Warrants				Total
	# of warrants (in thousands)		$		# of warrants (in thousands)		$		# of warrants (in thousands)		$
Balance at January 1, 2017	6,388		7,405		3,748		1,733		10,136		9,138
Conversion to equity (common shares) upon exercise of warrants	(2,865	)	(12,421	)	(2,010	)	(8,848	)	(4,875	)	(21,269	)
Revaluation of derivative warrant liability upon exercise of warrants	—		(3,844	)	—		(1,013	)	—		(4,857	)
Revaluation of derivative warrant liability	—		17,808		—		10,973		—		28,781
Balance at December 31, 2017	3,523		8,948		1,738		2,845		5,261		11,793

Balance at January 1, 2016	—		—		4,548		5,499		4,548		5,499
Issuance of warrants pursuant to December 28, 2016 financing	6,388		7,223		—		—		6,388		7,223
Conversion to equity (common shares) upon exercise of warrants	—		—		(800	)	(1,852	)	(800	)	(1,852	)
Revaluation of derivative warrant liability	—		182		—		(1,914	)	—		(1,732	)
Balance at December 31, 2016	6,388		7,405		3,748		1,733		10,136		9,138

The following assumptions were used to estimate the fair value of the derivative warrant liability on December 31, 2017 and December 31, 2016.

The following assumptions were used to estimate the fair value of the derivative warrant liability on December 31, 2017 and December 31, 2016.