Note 15 - Supplemental Selected Quarterly Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues	$ 150,587	$ 154,170	$ 163,644	$ 208,464	$ 306,162	$ 296,964	$ 272,466	$ 242,824	$ 676,865	$ 1,118,416	$ 1,042,356
Operating Income (loss)	(94,282)	(9,263)	(1,682)	6,128	38,591	39,432	31,816	20,757	(99,099)	130,596	94,445
Income (loss) from continuing operations	(83,096)	(4,471)	(4,254)	993	23,446	23,492	20,329	11,742	(90,828)	79,009	52,622
Net income (loss)	$ (83,096)	$ (4,471)	$ (4,254)	$ 993	$ 23,446	$ 23,492	$ 20,329	$ 35,011	$ (90,828)	$ 102,278	$ 65,323
Income (loss) from continuing operations (in dollars per share)	$ (1)	$ (0.05)	$ (0.05)	$ 0.01	$ 0.29	$ 0.29	$ 0.24	$ 0.14	$ (1.10)	$ 0.95	$ 0.62
Net income (loss) (in dollars per share)	(1)	(0.05)	(0.05)	0.01	0.29	0.29	0.24	0.41	(1.10)	1.23	0.77
Income (loss) from continuing operations (in dollars per share)	(1)	(0.05)	(0.05)	0.01	0.25	0.25	0.21	0.13	(1.10)	0.84	0.56
Net income (loss) (in dollars per share)	$ (1)	$ (0.05)	$ (0.05)	$ 0.01	$ 0.25	$ 0.25	$ 0.21	$ 0.36	$ (1.10)	$ 1.07	$ 0.69