Earnings Per Share - Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Computations (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
Numerator / net (loss)
(Loss) income and shares used in basic calculations	$ (11,214)	$ 21,937	$ 59,505	$ 252,076
Denominator / shares
(Loss) income and shares used in basic calculations (in shares)	85,009	91,134	86,531	104,244
(Loss) income and shares used in diluted calculations (in shares)	85,009	92,079	88,481	106,816
Basic (loss) earnings per common share (in dollars per share)	$ (0.13)	$ 0.24	$ 0.69	$ 2.42
Diluted (loss) earnings per common share (in dollars per share)	$ (0.13)	$ 0.24	$ 0.67	$ 2.36
Restricted awards
Denominator / shares
Effect of dilutive stock based awards (in shares)	0	809	1,066	1,994
Stock options and SARs
Denominator / shares
Effect of dilutive stock based awards (in shares)	0	136	546	390
Warrants
Denominator / shares
Effect of dilutive stock based awards (in shares)	0	0	338	188