Note 10 - Income Taxes Reconciliation of Taxes from Statutory Rate to Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal Statutory Income Tax Rate	21.00%	21.00%	35.00%
Provision for income taxes computed at the statutory tax rate	$ 178,289	$ 143,679	$ 121,358
Repurchase premium on convertible notes	0	0	(96)
State tax provision (benefit), net of federal impact	(293)	5,570	(15,641)
Valuation allowance	1,941	(1,856)	18,197
Remeasurement of net deferred tax assets due to the TCJA	0	0	102,617
Impact related to settlement of IRS Matter	0	(73,585)	0
Other, net	(3,253)	4,367	(786)
Total income tax provision (benefit)	$ 176,684	$ 78,175	$ 225,649