Note 2 - Net Income Per Share Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income (loss)—diluted		$ (29,951)	$ 166,730	$ 110,510	$ 337,687
Dilutive effect of share-based compensation arrangements	[1]	0	5,506	1,201	5,236
Adjusted average common shares outstanding—diluted		193,299	213,603	198,746	216,500
Net income (loss) per share—diluted		$ (0.15)	$ 0.78	$ 0.56	$ 1.56
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income (loss) - basic		$ (29,951)	$ 166,730	$ 110,510	$ 337,687
Average common shares outstanding - basic	[2]	193,299	208,097	197,545	211,264
Net income (loss) per share - basic		$ (0.15)	$ 0.80	$ 0.56	$ 1.60
Stock Compensation Plan
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Shares of common stock equivalents		2,295	168	1,213	168

[1] There were no dilutive shares for the three months ended June 30, 2020, 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 were not included in the calculation of diluted net income (loss) per share because they were anti-dilutive: Three Months Ended
June 30,Six Months Ended
June 30,(In thousands)2020201920202019Shares of common stock equivalents2,295  168  1,213  168  

[2] Includes the impact of fully vested shares under our share-based compensation programs.