Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2016
Basic EPS
Net income (loss)	$ 55,352	$ (367,183)	$ (1,186,874)
Weighted average shares
Basic (in shares)	159,853,000	129,639,000	102,441,000
Effect of stock-based compensation plans (in shares)	3,606,000	0	0
Diluted (in shares)	163,459,000	129,639,000	102,441,000
Income (loss) per share
Basic (in dollars per share)	$ 0.35	$ (2.83)	$ (11.59)
Diluted (in dollars per share)	$ 0.34	$ (2.83)	$ (11.59)
Convertible Senior Notes Due March 2028 [Member]
Earnings Per Share (Textual) [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	3.25%	3.25%		3.25%
Stock Options [Member]
Earnings Per Share (Textual) [Abstract]
Number of shares of common stock equivalents related to convertible debt	386,771	3,239,425	1,871,681