Note 13 - Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Taxes at statutory federal income tax rate, amount									$ 8,504	$ 5,324	$ 1,270
Taxes at statutory federal income tax rate									35.00%	35.00%	34.00%
Graduated tax rates, amount									$ (243)	$ (94)	$ 0
Graduated tax rates									(1.00%)	(0.60%)
State income tax—net of federal benefits, amount									$ 865	$ 484	$ 42
State income tax—net of federal benefits									3.60%	3.20%	1.10%
Valuation allowance—net, amount									$ (897)	$ 0	$ (21,060)
Valuation allowance—net									(3.70%)	0.00%	(563.70%)
Earnings on life insurance policies, amount									$ (549)	$ (515)	$ (388)
Earnings on life insurance policies									(2.30%)	(3.40%)	(10.40%)
Nontaxable investments, amount									$ (677)	$ (619)	$ (451)
Nontaxable investments									(2.80%)	(4.10%)	(12.00%)
Other—net, amount									$ (144)	$ 59	$ 17
Other—net									(0.60%)	0.40%	0.40%
Total, amount	$ 2,192	$ 2,384	$ 847	$ 1,436	$ 972	$ 1,529	$ 1,253	$ 885	$ 6,859	$ 4,639	$ (20,570)
Total									28.20%	30.50%	(550.60%)