Reconciliation of Earnings Per Share (EPS) - Earnings Per Share Reconciliation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income (Loss), Basic EPS	$ 36,759	$ (111,601)	$ (166,357)	$ (127,021)
Basic Average Common Shares Outstanding (in shares)	97,067	73,452	91,850	73,143
Earnings Per Share, Basic (in dollars per share)	$ 0.38	$ (1.52)	$ (1.81)	$ (1.74)
Effect of dilutive securities
Net Income (Loss), Diluted EPS	$ 36,759	$ (111,601)	$ (166,357)	$ (127,021)
Diluted Average Common Shares Outstanding (in shares)	97,389	73,452	91,850	73,143
Earnings Per Share, Diluted (in dollars per share)	$ 0.38	$ (1.52)	$ (1.81)	$ (1.74)
Stock options
Effect of dilutive securities
Effect of dilutive securities	11	0	0	0
Non-vested restricted stock
Effect of dilutive securities
Effect of dilutive securities	184	0	0	0
Performance share awards
Effect of dilutive securities
Effect of dilutive securities	127	0	0	0