Note 1 - Business and Significant Accounting Policies - Cash and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash and cash equivalents	$ 98,802	$ 47,818	$ 230,214
Restricted Cash and Cash Equivalents, Total	78,693	48,825	34,262
Total Cash and cash equivalents and restricted cash and cash equivalents	$ 177,495	$ 96,643	$ 264,476	$ 235,422