Earnings Per Share (Details 1) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Participating Securities, Distributed and Undistributed Earnings of Net Income, Percent	0.80%	0.87%	0.72%	0.80%
Earnings (loss) per share – Basic:
Net income (loss)	$ (7,116)	$ 20,030	$ 35,323	$ 56,292
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	0	174	255	448
Earnings (loss) available to common shareholders – Basic	$ (7,116)	$ 19,856	$ 35,068	$ 55,844
Weighted-average common shares outstanding – Basic	78,176,705	78,159,280	78,176,705	78,351,369
Earnings (loss) per common share – Basic	$ (0.09)	$ 0.25	$ 0.45	$ 0.71
Earnings (loss) per share – Diluted:
Net income (loss)	$ (7,116)	$ 20,030	$ 35,323	$ 56,292
Earnings (loss) available to common shareholders – Diluted	$ (7,116)	$ 19,856	$ 35,068	$ 55,844
Weighted-average common shares outstanding – Basic	78,176,705	78,159,280	78,176,705	78,351,369
Effect of dilutive shares(2)	0	0	227,350	0
Weighted-average common shares outstanding – Diluted	78,176,705	78,159,280	78,404,055	78,351,369
Earnings per common share – Diluted	$ (0.09)	$ 0.25	$ 0.45	$ 0.71
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	170,116