Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss) Attributable to Parent	$ 158,465	$ 7,082	$ 132,383	$ (43,456)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	139	39	241	0
Net loss available to common stockholders, basic	158,326	7,043	132,142	(43,456)
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	0	0	1	0
Net Income (Loss) Available to Common Stockholders, Diluted	$ 158,326	$ 7,043	$ 132,143	$ (43,456)
Weighted Average Number of Shares Outstanding, Basic	50,554,234	50,124,302	50,462,990	50,024,047
Weighted Average Number Diluted Shares Outstanding Adjustment	45,740	494,455	221,735	0
Weighted Average Number of Shares Outstanding, Diluted	50,599,974	50,618,757	50,684,725	50,024,047
Earnings Per Share, Basic	$ 3.13	$ 0.14	$ 2.62	$ (0.87)
Earnings Per Share, Diluted	$ 3.13	$ 0.14	$ 2.61	$ (0.87)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	6,029,156	3,593,708	4,618,618	4,410,974
Maximum [Member]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 6.75	$ 13.38	$ 6.75	$ 13.38