Note 6 - Marketable Securities - Securitizations Trusts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017
Principal Outstanding		[1]	$ 2,714,823
Assets on Balance Sheet		[2]	11,794
Liabilities on Balance Sheet	0
Maximum Exposure to Loss			11,794
Year to Date Loss on Sale	0
Year to Date Cash Flows	$ 1,057		$ 3,193

[1] Principal Outstanding is the aggregate principal of the underlying loans held by the securitization trusts.

[2] Assets on Balance Sheet and Maximum Exposure to Loss is the estimated fair value of securities issued by the entity and recorded as marketable securities, current in the consolidated balance sheets.