Note 2 - Net Income Per Share Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income From continuing operations - diluted		$ 83,651	$ 73,805	$ 252,315	$ 218,105
Net income - diluted		$ 83,651	$ 73,805	$ 252,315	$ 223,490
Dilutive effect of stock-based compensation arrangements (2)	[1]	3,129	3,323	2,846	3,075
Adjusted average common shares outstanding - diluted		225,968	250,795	230,672	246,993
Net income from continuing operations, per diluted share		$ 0.37	$ 0.29	$ 1.09	$ 0.88
Income from discontinued operations and disposal of discontinued operations, net of tax, per diluted share		0.00	0.00	0.00	0.02
Net income per share - diluted		$ 0.37	$ 0.29	$ 1.09	$ 0.90
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income from continuing operations - basic		$ 82,803	$ 70,091	$ 247,164	$ 207,011
Income (loss) from discontinued operations, net of tax		0	0	0	5,385
Net income - basic		$ 82,803	$ 70,091	$ 247,164	$ 212,396
Average common shares outstanding - basic		214,387	207,938	210,858	197,562
Net income from continuing operations, per basic share		$ 0.39	$ 0.34	$ 1.17	$ 1.05
Income from discontinued operations and disposal of discontinued operations, net of tax, per basic share		0.00	0.00	0.00	0.03
Net income per share - basic		$ 0.39	$ 0.34	$ 1.17	$ 1.08
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]	$ 848	$ 3,714	$ 5,151	$ 11,094
Dilutive effect of Convertible Senior Notes		8,274	37,736	16,897	37,736
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]	178	1,798	71	8,620
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		1,045	469	1,045	730
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	0	1,902	0

[1] The following number of shares of our common stock equivalents issued under our stock-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 EndedSeptember 30, Nine Months EndedSeptember 30,(in thousands)2016 2015 2016 2015Shares of common stock equivalents1,045 469 1,045 730Shares 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.