Note 2 - Recently Issued and Adopted Accounting Pronouncements (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018	Sep. 30, 2018
Operating Lease, Right-of-Use Asset	$ 70,472		$ 0	$ 0
Operating Lease, Liability, Current	16,000
Operating Lease, Liability, Noncurrent	56,740		0	0
Retained Earnings (Accumulated Deficit), Ending Balance	$ 656,487		$ 787,356	$ 786,936
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset		$ 500
Operating Lease, Liability, Current		72,200
Operating Lease, Liability, Noncurrent		14,900
Retained Earnings (Accumulated Deficit), Ending Balance		$ 60,400