Note 15 - Balance Sheet Offsetting (Details) - Financial Instruments That Are Eligible for Offset in the Consolidated Balance Sheet - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Liabilities:
Securities sold under agreements to repurchase, gross	$ 400,000	$ 400,000
Securities sold under agreements to repurchase, net	400,000	400,000
Securities sold under agreements to repurchase, collateral posted	(400,000)	(400,000)
Derivatives, gross	14,878	6,496
Derivatives, net	14,878	6,496
Derivatives, collateral posted	$ (14,878)	$ (6,496)