Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic Net Income (Loss) Per Share
Net income (loss)	$ (187,083)	$ 24,047
Weighted average common shares outstanding	195,260,000	187,184,000
Basic net income (loss) per share	$ (0.96)	$ 0.13
Diluted Net Income (Loss) Per Share
Diluted net income (loss)	$ (187,083)	$ 24,047
Weighted average common shares outstanding	195,260,000	187,184,000
Dilutive stock options and RSU’s		5,441,000
Weighted average shares used to compute diluted net income (loss) per share	195,260,000	192,625,000
Diluted net income (loss) per share	$ (0.96)	$ 0.12
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation	13,510,411	17,138,793
Stock Options
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation	12,598,407	2,652,265
0.375% Convertible Senior Notes due 2018
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation	505,004	7,245,244
1.25% Convertible Senior Notes due 2020
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation	407,000	7,241,284