Note 18 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Stockholders' Equity Attributable to Parent, Ending Balance	$ 2,009,792		$ 1,973,304
Stockholders' Equity, Period Increase (Decrease), Total	36,500		$ 63,800
Dividends, Common Stock, Cash	19,500
Other Comprehensive Income (Loss), Net of Tax, Total	$ (9,321)	$ 73
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	578,238		943,327
U.S. Treasury [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,846,374
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 20.96		$ 20.41
Class of Warrant or Right, Increase in Warrants Exercisable, Percentage			1.03%