Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Basic EPS
Net income (loss)	$ 14,497	$ (16,677)	$ (5,899)	$ (49,965)
Weighted average shares
Basic (in shares)	153,972,000	135,036,000	152,110,000	118,897,000
Effect of stock-based compensation plans (in shares)	3,928,000	0	0	0
Diluted (in shares)	157,900,000	135,036,000	152,110,000	118,897,000
Income (loss) per share
Basic (in dollars per share)	$ 0.09	$ (0.12)	$ (0.04)	$ (0.42)
Diluted (in dollars per share)	$ 0.09	$ (0.12)	$ (0.04)	$ (0.42)
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	439,721	3,375,337	1,600,669	3,415,129,000,000