Note 13 - Unaudited Quarterly Financial Data - Summarized Quarterly Financial Data (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
Revenue	$ 26,617	$ 27,821	$ 30,487	$ 38,794	$ 50,585	$ 60,668	$ 74,461	$ 89,092	$ 123,719	$ 274,806	$ 495,769
Operating income (loss)	(16,965)	(19,766)	(66,338)	(128,256)	(11,706)	(167,081)	(4,207)	(558)	(231,325)	(183,552)	101,665
Net income (loss)	$ (39,488)	$ (24,729)	$ (47,580)	$ (91,182)	$ (16,638)	$ (185,226)	$ (8,245)	$ (5,126)	$ (202,979)	$ (215,235)	$ 62,375
Basic (in dollars per share)	$ (1.57)	$ (0.98)	$ (1.90)	$ (3.66)	$ (0.67)	$ (7.48)	$ (0.33)	$ (0.21)	$ (8.09)	$ (8.70)	$ 2.39
Diluted (in dollars per share)	$ (1.57)	$ (0.98)	$ (1.90)	$ (3.66)	$ (0.67)	$ (7.48)	$ (0.33)	$ (0.21)	$ (8.09)	$ (8.70)	$ 2.39