Note 3 - Components of Share-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restricted Stock [Member]
Pretax compensation expense	$ 8,939	$ 8,053	$ 16,907	$ 15,704
Tax benefit	3,397	3,068	6,425	5,983
Allocated share-based compensation expense, net of tax	5,542	4,985	10,482	9,721
Performance Shares [Member]
Pretax compensation expense	3,004	2,515	6,008	4,993
Tax benefit	1,142	958	2,283	1,902
Allocated share-based compensation expense, net of tax	$ 1,862	$ 1,557	$ 3,725	$ 3,091