Note 11 - Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal									$ 26,820	$ 59,433	$ 28,788
State									36,639	28,278	22,364
Total Current									63,459	87,711	51,152
Deferred:
Federal									1,495	31,818	11,775
State									848	2,736	4,174
Total Deferred									2,343	34,554	15,949
Total income tax expense	$ 17,193	$ 18,698	$ 11,046	$ 18,866	$ 51,166	$ 35,163	$ 15,431	$ 20,505	$ 65,802	$ 122,265	$ 67,101