Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (14,066)	$ (25,039)
Less: Earnings allocated to unvested restricted stock awards	0	0
Earnings (loss) allocated to common shareholders	$ (14,066)	$ (25,039)
Common stock:
Weighted average basic shares outstanding (in shares)	64,804	64,004
Effect of dilutive securities (in shares)	0	0
Weighted average diluted shares outstanding (in shares)	64,804	64,004
Basic earnings (loss) per share:
Net loss (in dollars per share)	$ (0.22)	$ (0.39)
Diluted earnings (loss) per share:
Net loss (in dollars per share)	$ (0.22)	$ (0.39)