Note 1 - Summary of Business and Significant Accounting Policies (Details Textual) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)		Jan. 01, 2019 USD ($)	Dec. 31, 2017 USD ($)
Net Income (Loss) Attributable to Parent, Total	$ (4,606)		$ (9,112)	$ (41,244)
Retained Earnings (Accumulated Deficit), Ending Balance	(269,319)			(264,713)	[1]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	8,866		$ 23,276	11,503			$ 28,837
Accounts Receivable, Allowance for Credit Loss, Ending Balance	2,567			2,651
Financing Receivable, Allowance for Credit Loss, Ending Balance	$ 381			353
Number of Reporting Units	1
Goodwill, Impairment Loss	$ 0	$ 14,740
Impairment of Long-Lived Assets Held-for-use	0			0
Operating Lease, Right-of-Use Asset	11,787				[1]
Operating Lease, Liability, Total	13,441
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset						$ 14,589
Operating Lease, Liability, Total						$ 16,425
Shelf Registration Statement [Member] | JMP Securities, LLC [Member]
Equity and Debt Securities, Offering Price	13,000
Maximum [Member] | Shelf Registration Statement [Member]
Equity and Debt Securities, Offering Price	$ 50,000

[1] Derived from the Company's audited consolidated financial statements as of December 31, 2018.