Note 1 - Summary of Significant Accounting Policies - Effect of the Accounting Change on the Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net cash provided by operating activities	$ 90,882	$ 83,355	$ 81,939
Net cash used in investing activities	(81,476)	(72,784)	(67,031)
Net Decrease in Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents	(17,725)	(31,104)	(15,216)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning of Period	49,314	80,418	95,634
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, End of Period	31,589	49,314	80,418
New Accounting Pronouncement, Early Adoption, Effect [Member]
Restricted cash and cash equivalents
Net cash provided by operating activities		83,355	81,939
Change in restricted cash and cash equivalents
Net cash used in investing activities		(72,784)	(67,031)
Net Decrease in Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents		(31,104)	(15,216)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning of Period	49,314	80,418	95,634
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, End of Period		49,314	80,418
New Accounting Pronouncement, Early Adoption, Effect [Member] | Scenario, Previously Reported [Member]
Restricted cash and cash equivalents		(9,392)	(6,245)
Net cash provided by operating activities		73,963	75,694
Change in restricted cash and cash equivalents		8,937	9,523
Net cash used in investing activities		(63,847)	(57,508)
Net Decrease in Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents		(31,559)	(11,938)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning of Period	38,208	69,767	81,705
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, End of Period		38,208	69,767
New Accounting Pronouncement, Early Adoption, Effect [Member] | Restatement Adjustment [Member]
Restricted cash and cash equivalents		9,392	6,245
Net cash provided by operating activities		9,392	6,245
Change in restricted cash and cash equivalents		(8,937)	(9,523)
Net cash used in investing activities		(8,937)	(9,523)
Net Decrease in Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents		455	(3,278)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning of Period	$ 11,106	10,651	13,929
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, End of Period		$ 11,106	$ 10,651