Note 19 - Stockholders' Equity (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity Attributable to Parent, Ending Balance	$ 2,313,037	$ 2,163,329	$ 2,294,283	$ 2,121,866
Stockholders' Equity, Period Increase (Decrease), Total	18,800
Net Income (Loss) Attributable to Parent, Total	46,852	66,679
Other Comprehensive Income (Loss), Net of Tax, Total	7,575	7,575
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	846	835
Dividends, Common Stock, Cash	24,660	24,967
Payments for Repurchase of Common Stock	$ 12,880	$ 8,601