Selected Quarterly Financial Data (Unaudited) - Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions
Revenues	$ 8,727	$ 294,448	$ 9,682	$ 9,216	$ 17,071	$ 6,966	$ 13,798	$ 25,374	$ 322,073	$ 63,209	$ 91,689
Income (Loss) From Operations	(47,217)	224,676	(18,545)	(17,469)	(12,367)	(22,927)	(30,272)	(37,713)	141,445	(103,279)	(130,624)
Net loss	$ (51,138)	$ 226,086	$ (23,018)	$ (21,797)	$ (16,782)	$ (27,396)	$ (34,549)	$ (41,821)	$ 130,133	$ (120,548)	$ (122,993)
Earnings Per Share, Basic and Diluted					$ (0.16)	$ (0.26)	$ (0.33)	$ (0.40)
Weighted Average Number of Shares Outstanding, Basic and Diluted					105,920	105,881	105,848	105,668
Weighted Average Number of Shares Issued, Basic	106,272	106,272	106,272	106,054					106,218	105,830	105,237
Weighted Average Number of Shares Outstanding, Diluted	106,272	116,640	106,272	106,054					116,747	105,830	105,237
Earnings Per Share, Diluted	$ (0.48)	$ 1.95	$ (0.22)	$ (0.21)					$ 1.16	$ (1.14)	$ (1.17)
Earnings Per Share, Basic	$ (0.48)	$ 2.13	$ (0.22)	$ (0.21)					$ 1.23	$ (1.14)	$ (1.17)