Selected Quarterly Financial Data (Unaudited) - Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions
Revenues	$ 23,995	$ 322,073	$ 63,209
Income (Loss) From Operations	(47,800)	141,445	(103,279)
Net loss	$ (58,574)	$ 130,133	$ (120,548)
Weighted Average Number of Shares Issued, Basic	110,841	106,218	105,830
Weighted Average Number of Shares Outstanding, Diluted	110,841	116,747	105,830
Earnings Per Share, Diluted	$ (0.53)	$ 1.16	$ (1.14)
Earnings Per Share, Basic	$ (0.53)	$ 1.23	$ (1.14)