Note 4 - Earnings Per Share (Details) - Earnings Per Share - Basic and Diluted Loss Per Share (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator
Net income	$ 15,458	$ 36,251	$ 48,504	$ 283,676
Less: distributed earnings allocated to participating securities	(48)		(150)
Less: undistributed earnings allocated to participating securities	(13)	(294)	(51)	(2,609)
Net income attributable to common stockholders (numerator for basic earnings per share)	15,397	35,957	48,303	281,067
Add back: undistributed earnings allocated to participating securities	13	294	51	2,609
Less: undistributed earnings reallocated to participating securities	(13)	(293)	(51)	(2,586)
Numerator for diluted earnings per share under two class method	$ 15,397	$ 35,958	$ 48,303	$ 281,090
Denominator
Weighted-average common shares outstanding (in Shares)	48,625,685	48,478,403	48,607,425	48,423,969
Denominator for diluted earnings per share under two class method (in Shares)	48,830,790	48,753,649	48,824,871	48,852,870
Basic Earnings Per Common Share (in Dollars per share)	$ 0.32	$ 0.74	$ 0.99	$ 5.80
Diluted Earnings Per Common Share (in Dollars per share)	$ 0.32	$ 0.74	$ 0.99	$ 5.75
Employee Stock Option [Member]
Denominator
Add: dilutive effect of stock options (in Shares)	205,105	275,246	217,446	428,901