Note 12 - Stock Repurchase Program (Details Textual) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended		35 Months Ended
	Oct. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Aug. 31, 2015
Stock Repurchase Program, Authorized Amount	$ 250,000				$ 200,000
Stock Repurchase Program, Period in Force	2 years
Payments for Repurchase of Common Stock		$ 25,656	$ 30,012	$ 305,547
Treasury Stock [Member]
Shares Acquired Under Stock Repurchases Program, Shares		560,000	844,500	8,676,706