Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator for Basic and Diluted Earnings per Share - [Abstract]
Net Income (Loss)	$ (142,352)		$ (190,000)		$ (292,558)		$ (471,776)		$ (284,296)		$ (4,075,739)		$ 5,268		$ (169,748)		$ (1,096,686)	$ (4,524,515)	$ 2,915,487
Denominator for Basic Earnings per Share - [Abstract]
Weighted Average Shares (in shares)																	553,384	545,697	543,443
Potential Dilutive Common Shares -[Abstract]
Stock Options/SARs (in shares)																	0	0	2,526
Restricted Stock/Units and Performance Units/Stock (in shares)																	0	0	2,570
Denominator for Diluted Earnings per Share - [Abstract]
Adjusted Diluted Weighted Average Shares (in shares)	567,337		547,838		547,335		546,715		546,432		545,920		549,683		544,998		553,384	545,697	548,539
Net Income (Loss) Per Share [Abstract]
Basic (in dollars per share)	$ (0.25)	[1]	$ (0.35)	[1]	$ (0.53)	[1]	$ (0.86)	[1]	$ (0.52)	[1]	$ (7.47)	[1]	$ 0.01	[1]	$ (0.31)	[1]	$ (1.98)	$ (8.29)	$ 5.36
Diluted (in dollars per share)	$ (0.25)	[1]	$ (0.35)	[1]	$ (0.53)	[1]	$ (0.86)	[1]	$ (0.52)	[1]	$ (7.47)	[1]	$ 0.01	[1]	$ (0.31)	[1]	$ (1.98)	$ (8.29)	$ 5.32
Antidilutive Stock Options and SARs excluded from Diluted Earnings Per Share Calculation (in shares)																	10,300	10,200	700
Restricted Stock and Restricted Stock Units and Performance Units and Performance Stock Excluded from Calculation																	4,500	5,300

[1] The sum of quarterly net income (loss) per share may not agree with total year net income (loss) per share as each quarterly computation is based on the weighted average of common shares outstanding.