Note 6 - Leases (Details Textual) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2019	Sep. 30, 2019		Sep. 30, 2019		Dec. 31, 2018
Operating Lease, Right-of-Use Asset		$ 3,102		$ 3,102		$ 0
Operating Lease, Liability, Total		2,508		2,508
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2,200	$ 869	[1]	$ 3,450	[1]
Operating Lease, Weighted Average Remaining Lease Term		2 years 3 months 18 days		2 years 3 months 18 days
Operating Lease, Lease Income, Lease Payments		$ 500		$ 1,300
Maximum [Member]
Lessee, Operating Lease, Term of Contract		4 years		4 years
Lessee, Operating Lease, Renewal Term		5 years		5 years
Operating Lease, Weighted Average Remaining Lease Term		5 years		5 years
Lessor, Operating Lease, Renewal Term		5 years		5 years
Minimum [Member]
Operating Lease, Weighted Average Remaining Lease Term		2 years		2 years

[1] For the nine months ended September 30, 2019, the amount includes $2.2 million for operating leases existing on January 1, 2019.