Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator for Basic and Diluted Earnings Per Share - [Abstract]
Net Income (Loss)	$ 100,541	$ (190,000)	$ 152,111	$ (954,334)
Denominator for Basic Earnings Per Share - [Abstract]
Weighted Average Shares	574,783	547,838	574,370	547,295
Denominator for Diluted Earnings Per Share - [Abstract]
Adjusted Diluted Weighted Average Shares	578,736	547,838	578,453	547,295
Net Income (Loss) Per Share
Basic	$ 0.17	$ (0.35)	$ 0.26	$ (1.74)
Diluted	$ 0.17	$ (0.35)	$ 0.26	$ (1.74)
Stock Options And SARs [Member]
Potential Dilutive Common Shares - [Abstract]
Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangments	1,451	0	1,518	0
Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract]
Anti-dilutive Securities excluded from Diluted Earnings Per Share Calculation	4,200	9,900	3,600	10,200
Restricted Stock/Units and Performance Units/Stock [Member]
Potential Dilutive Common Shares - [Abstract]
Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangments	2,502	0	2,565	0
Antidilutive Securities Excluded from Computation of Earnings Per Share [Abstract]
Anti-dilutive Securities excluded from Diluted Earnings Per Share Calculation		4,600		4,600