Note 1 - Interim Financial Statements - Reconciliation of Earnings (Loss) and the Weighted Average Number of Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income/(loss) available to the Company's common shareholders		$ 101,957	$ (55,100)	$ 298,996	$ 265,912
Earnings attributable to participating securities		(526)	(502)	(1,596)	(1,493)
Net income/(loss) available to the Company’s common shareholders for basic earnings/(loss) per share		101,431	(55,602)	297,400	264,419
Distributions on convertible units		24		43
Net income/(loss) available to the Company’s common shareholders for diluted earnings/(loss) per share		$ 101,455	$ (55,602)	$ 297,443	$ 264,419
Weighted average common shares outstanding – basic (in shares)		423,688	420,073	423,574	416,829
Effect of dilutive securities (a):
Equity awards (in shares)	[1]	513		556	1,405
Assumed conversion of convertible units (in shares)	[1]	110		63
Weighted average common shares outstanding – diluted (in shares)		424,311	420,073	424,193	418,234
-Basic (in dollars per share)		$ 0.24	$ (0.13)	$ 0.70	$ 0.63
-Diluted (in dollars per share)		$ 0.24	$ (0.13)	$ 0.70	$ 0.63

[1] The effect of the assumed conversion of certain convertible units had an anti-dilutive effect upon the calculation of Income from continuing operations per share. Accordingly, the impact of such conversions has not been included in the determination of diluted earnings/(loss) per share calculations. Additionally, there were 2,314,908 and 3,545,000 stock options that were not dilutive as of September 30, 2017 and 2016, respectively.