Note 11 - Business Segments and Significant Customers (Details) - Long-lived Assets by Geographic Area - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Note 11 - Business Segments and Significant Customers (Details) - Long-lived Assets by Geographic Area [Line Items]
Long-lived assets	$ 1,896,811	$ 1,831,564
UNITED STATES
Note 11 - Business Segments and Significant Customers (Details) - Long-lived Assets by Geographic Area [Line Items]
Long-lived assets	1,150,521	1,081,699
CANADA
Note 11 - Business Segments and Significant Customers (Details) - Long-lived Assets by Geographic Area [Line Items]
Long-lived assets	741,612	749,810
MEXICO
Note 11 - Business Segments and Significant Customers (Details) - Long-lived Assets by Geographic Area [Line Items]
Long-lived assets	$ 4,678	$ 55