Reconciliation of Earnings Per Share (EPS) - Earnings Per Share Reconciliation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income (Loss), Basic EPS	$ 53,314	$ (227,904)	$ (113,043)	$ (354,925)
Basic Average Common Shares Outstanding (in shares)	97,068	78,742	93,602	75,125
Earnings Per Share, Basic (in dollars per share)	$ 0.55	$ (2.89)	$ (1.21)	$ (4.72)
Effect of dilutive securities
Net Income (Loss), Diluted EPS	$ 53,314	$ (227,904)	$ (113,043)	$ (354,925)
Diluted Average Common Shares Outstanding (in shares)	97,511	78,742	93,602	75,125
Earnings Per Share, Diluted (in dollars per share)	$ 0.55	$ (2.89)	$ (1.21)	$ (4.72)
Stock options
Effect of dilutive securities
Effect of dilutive securities (in shares)	54	0	0	0
Non-vested restricted stock
Effect of dilutive securities
Effect of dilutive securities (in shares)	217	0	0	0
Performance share awards
Effect of dilutive securities
Effect of dilutive securities (in shares)	172	0	0	0