Note 10 - Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal		$ 25,201	$ 21,167	$ 2,577
International		5,674	10,491	10,076
Total current		30,875	31,658	12,653
Deferred:
Federal		7,615	8,350	22,005
International	$ (3,599)	(429)	206	(2,269)
Total deferred		7,186	8,556	19,736
Total income tax expense		$ 38,061	$ 40,214	$ 32,389