Net Income (Loss) Per Share - Schedule of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ (67,446)	$ 50,021	$ (102,888)	$ (66,329)
Weighted average common shares outstanding - basic (in shares)	159,304	143,357	156,799	142,876
Dilutive potential common shares (in shares)	0	4,711	0	0
Weighted average common shares outstanding - diluted (in shares)	159,304	148,068	156,799	142,876
Net income (loss) per share - basic (in dollars per share)	$ (0.42)	$ 0.35	$ (0.66)	$ (0.46)
Net income (loss) per share - diluted (in dollars per share)	$ (0.42)	$ 0.34	$ (0.66)	$ (0.46)