Earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator
Net income (loss) - basic (in dollars)	$ (16,926)	$ 21,901
Net income (loss) - diluted (in dollars)	$ (16,926)	$ 21,901
Denominator
Weighted-average number of shares - basic	47,988,630	30,299,650
Dilutive securities - share-based awards (in shares)		1,052,730
Dilutive securities - common stock warrants (in shares)		109,316
Weighted average number of shares - diluted (in shares)	47,988,630	31,461,696
Net income (loss) per share - basic (in dollars per share)	$ (0.35)	$ 0.72
Net income (loss) per share - diluted (in dollars per share)	$ (0.35)	$ 0.70