(Loss) Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic (Loss) Earnings Per Share
Undistributed net (loss) income from operations	$ (36,316)	$ 42,861	$ (43,667)	$ 43,312
Basic net (loss) income attributable to common shares	$ (36,316)	$ 42,861	$ (43,667)	$ 43,312
Basic weighted average shares outstanding (in shares)	20,332,970	20,125,419	20,279,022	20,091,568
Basic undistributed net income (loss) per share attributable to common shares (USD per share)	$ (1.79)	$ 2.13	$ (2.15)	$ 2.16
Diluted (Loss) Earnings Per Share
Undistributed net (loss) income from operations	$ (36,316)	$ 42,861	$ (43,667)	$ 43,312
Diluted net (loss) income attributable to common shares	$ (36,316)	$ 42,861	$ (43,667)	$ 43,312
Basic weighted average shares outstanding (in shares)	20,332,970	20,125,419	20,279,022	20,091,568
Effect of dilutive options and restricted share units (in shares)	0	192,000	0	176,000
Diluted weighted average shares outstanding (in shares)	20,332,970	20,317,328	20,279,022	20,268,393
Diluted undistributed net income (loss) per share attributable to common shares (USD per share)	$ (1.79)	$ 2.11	$ (2.15)	$ 2.14