Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of basic and diluted earnings per share (EPS)
Net income/(loss)	$ (6,734,000)	$ (2,653,000)	$ 25,893,000	$ (10,039,000)
Less: Preferred stock dividend	124,000	0	207,000	0
Less: Earnings attributable to participating securities	0	0	(3,059,000)	0
Income/(loss) attributable to common stockholders	(6,858,000)	(2,653,000)	22,627,000	(10,039,000)
Effect of dilutive securities:
Add back: Allocation of earnings to participating securities	$ 0	$ 0	3,059,000	0
Less: Re-allocation of earnings to participating securities considering potentially dilutive securities			(3,046,000)	0
Numerator for diluted EPS			$ 22,640,000	$ (10,039,000)
Basic Earnings/(Loss) per Common Share
Weighted-average common shares outstanding (shares)	6,226,000	6,190,000	6,220,000	6,179,000
Basic earnings/(loss) per common share (dollars per share)	$ (1.10)	$ (0.43)	$ 3.64	$ (1.62)
Diluted Earnings/(Loss) per Common Share
Weighted-average shares used to compute earnings/(loss) per share attributable to common shares (shares)	6,226,000	6,190,000	6,250,000	6,179,000
Diluted earnings/(loss) per common share (dollars per share)	$ (1.10)	$ (0.43)	$ 3.62	$ (1.62)
Computation of Shares Used in Diluted Earnings/(Loss) Per Common Share
Weighted-average common shares outstanding (shares)	6,226,000	6,190,000	6,220,000	6,179,000
Weighted average common equivalent shares-dilutive effect of unvested shares (shares)			30,000	0.00
Weighted-average common and common equivalent shares outstanding (shares)	6,226,000	6,190,000	6,250,000	6,179,000
Stock Options
Stock-based compensation arrangement by stock-based payment award
Weighted-average anti-dilutive shares have been excluded from the EPS calculations (in shares)	300,000	300,000	300,000	300,000
Unvested Shares
Stock-based compensation arrangement by stock-based payment award
Weighted-average anti-dilutive shares have been excluded from the EPS calculations (in shares)	200,000	100,000	0	100,000
Preferred Stock
Stock-based compensation arrangement by stock-based payment award
Weighted-average anti-dilutive shares have been excluded from the EPS calculations (in shares)	1,000,000