Earnings Per Share (Details) - USD ($) $ / shares in Units, $ 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
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ (51,138)	$ 226,086	$ (23,018)	$ (21,797)	$ (16,782)	$ (27,396)	$ (34,549)	$ (41,821)	$ 130,133	$ (120,548)	$ (122,993)
Debt Instrument, Convertible, If-converted Value in Excess of Principal									$ 5,067	$ 0	$ 0
Shares used in computing net loss per common share, basic and diluted					105,920,000	105,881,000	105,848,000	105,668,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements									164,000	0	0
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities									10,365,000	0	0
Weighted Average Number of Shares Outstanding, Diluted	106,272,000	116,640,000	106,272,000	106,054,000					116,747,000	105,830,000	105,237,000
Earnings Per Share, Basic	$ (0.48)	$ 2.13	$ (0.22)	$ (0.21)					$ 1.23	$ (1.14)	$ (1.17)
Earnings Per Share, Diluted	$ (0.48)	$ 1.95	$ (0.22)	$ (0.21)					$ 1.16	$ (1.14)	$ (1.17)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									8,206,390	7,438,134	5,907,643
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities									$ 135,200	$ (120,548)	$ (122,993)
Weighted Average Number of Shares Issued, Basic	106,272,000	106,272,000	106,272,000	106,054,000					106,218,000	105,830,000	105,237,000