Selected Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ 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
Revenues		$ 174,280		$ 153,408		$ 138,305		$ 136,184		$ 172,292	$ 212,393	$ 214,447	$ 255,099	$ 602,177	$ 854,231	$ 1,572,944
Gross profit (loss)	[1]	37,773		(27,365)		(74,223)		(49,871)		(492,877)	(314,657)	(419,916)	(389,699)
Net income (loss)		$ 1,683		$ (24,022)		$ (72,136)		$ (41,149)		$ (309,337)	$ (205,281)	$ (274,389)	$ (248,354)	$ (135,624)	$ (1,037,361)	$ 136,276
Net income (loss) per common share:
Basic		$ 0.03		$ (0.48)		$ (1.44)		$ (0.83)		$ (6.29)	$ (4.18)	$ (5.58)	$ (5.07)	$ (2.71)	$ (21.12)	$ 2.80
Diluted		$ 0.03	[2]	$ (0.48)	[2]	$ (1.44)	[2]	$ (0.83)	[2]	$ (6.29)	$ (4.18)	$ (5.58)	$ (5.07)	$ (2.71)	$ (21.12)	$ 2.78

[1] Gross profit (loss) excludes general and administrative expense, interest expense, (gain) loss on disposition of assets, gain (loss) on derivatives, income taxes, and other income (loss).

[2] Due to the effect of the income in the fourth quarter, the diluted earnings per share for the year's four quarters does not equal annual loss per share.