Note 2 - Net Income Per Share Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders, Diluted		$ (27,342)	$ 99,025	$ 48,915	$ 168,664
Dilutive effect of share-based compensation arrangements (2)	[1]	0	2,989	3,896	2,698
Adjusted average common shares outstanding—diluted		215,152	226,203	220,474	232,945
Net income (loss)—diluted		$ (0.13)	$ 0.44	$ 0.22	$ 0.73
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss)—basic		$ (27,342)	$ 98,112	$ 49,130	$ 164,361
Average common shares outstanding - basic		215,152	214,274	215,054	208,991
Net income per share - basic		$ (0.13)	$ 0.46	$ 0.23	$ 0.79
Convertible Debt | Convertible Senior Notes Due 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Adjustment for dilutive Convertible Senior Notes due 2019, net of tax (1)	[2]	$ 0	$ 913	$ (215)	$ 4,303
Dilutive effect of Convertible Senior Notes due 2017 (2)		0	8,928	922	21,256
Convertible Debt | Convertible Senior Notes Due 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of Convertible Senior Notes due 2017 (2)	[1]	0	12	602	0
Stock Compensation Plan [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		5,975	1,042	442	1,042
Convertible Debt Securities [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		509	0	0	1,902

[1] There were no dilutive shares for the three months ended June 30, 2017, as a result of our net loss for the period. The following number of shares of our common stock equivalents issued under our share-based compensation arrangements and our convertible debt were not included in the calculation of diluted net income (loss) per share because they were anti-dilutive: Three Months EndedJune 30, Six Months EndedJune 30,(In thousands)2017 2016 2017 2016Shares of common stock equivalents5,975 1,042 442 1,042Shares of Convertible Senior Notes due 2017509 — — 1,902

[2] As applicable, includes coupon interest, amortization of discount and fees, and other changes in income or loss that would result from the assumed conversion. Included in the six months ended June 30, 2017 is a benefit related to our adjustment of estimated accrued expense to actual amounts, resulting from the January 2017 settlement of our obligations on the remaining Convertible Senior Notes due 2019.