Note 6 - Leases (Details Textual) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2019		Dec. 31, 2018
Operating Lease, Right-of-Use Asset		$ 2,770	$ 2,770
Operating Lease, Liability, Total		2,154	2,154
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2,200	$ 100	$ 2,264	[1]
Minimum [Member]
Lessee, Operating Lease, Remaining Lease Term			1 year
Maximum [Member]
Lessee, Operating Lease, Remaining Lease Term			4 years
Lessee, Operating Lease, Renewal Term		5 years	5 years

[1] Includes $2.2 million for operating leases existing on January 1, 2019 and $0.1 million for new operating leases commenced during the three months ended March 31, 2019.