Note 2 - Net Income Per Share Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of share-based compensation arrangements (2)	[1]	4,017	2,418
Adjusted average common shares outstanding—diluted		221,497	239,707
Net income per share - diluted		$ 0.34	$ 0.29
Net Income (Loss) Available to Common Stockholders, Diluted		$ 76,257	$ 69,639
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income—basic		$ 76,472	$ 66,249
Average common shares outstanding - basic		214,925	203,706
Net income per share - basic		$ 0.36	$ 0.33
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]	$ (215)	$ 3,390
Dilutive effect of Convertible Senior Notes		1,854	33,583
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	[1]	701	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		445	709
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		0	1,902

[1] The following number of shares of our common stock equivalents issued under our share-based compensation arrangements and convertible debt were not included in the calculation of diluted net income per share because they were anti-dilutive: Three Months EndedMarch 31,(In thousands)2017 2016Shares of common stock equivalents445 709Shares of Convertible Senior Notes due 2017— 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. Due to the January 2017 settlement of our obligations on the remaining Convertible Senior Notes due 2019, a benefit was recorded to adjust estimated accrued expense to actual amounts.