Note 2 - Fair Value Measurement - Financial Assets and Liabilities on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets	$ 111,094	$ 7,448
Liabilities	2,300	41,516
Contingent Consideration Liabilities [Member]
Liabilities	386
Warrant Liabilities [Member]
Liabilities	1,914	39,602
Money Market Funds [Member]
Assets	93,984	6,448
Restricted Cash Held in Escrow [Member]
Assets	15,000
Convertible Debt Securities [Member]
Assets	2,110	1,000
Contingent Consideration Liabilities [Member]
Liabilities		1,914
Fair Value, Inputs, Level 1 [Member]
Assets	108,984	6,448
Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Contingent Consideration Liabilities [Member]
Liabilities	0
Fair Value, Inputs, Level 1 [Member] | Warrant Liabilities [Member]
Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets	93,984	6,448
Fair Value, Inputs, Level 1 [Member] | Restricted Cash Held in Escrow [Member]
Assets	15,000
Fair Value, Inputs, Level 1 [Member] | Convertible Debt Securities [Member]
Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Contingent Consideration Liabilities [Member]
Liabilities		0
Fair Value, Inputs, Level 2 [Member]
Assets	0	0
Liabilities	0	0
Fair Value, Inputs, Level 2 [Member] | Contingent Consideration Liabilities [Member]
Liabilities	0
Fair Value, Inputs, Level 2 [Member] | Warrant Liabilities [Member]
Liabilities	0	0
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Restricted Cash Held in Escrow [Member]
Assets	0
Fair Value, Inputs, Level 2 [Member] | Convertible Debt Securities [Member]
Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Contingent Consideration Liabilities [Member]
Liabilities		0
Fair Value, Inputs, Level 3 [Member]
Assets	2,110	1,000
Liabilities	2,300	41,516
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration Liabilities [Member]
Liabilities	386
Fair Value, Inputs, Level 3 [Member] | Warrant Liabilities [Member]
Liabilities	1,914	39,602
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Restricted Cash Held in Escrow [Member]
Assets	0
Fair Value, Inputs, Level 3 [Member] | Convertible Debt Securities [Member]
Assets	$ 2,110	1,000
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration Liabilities [Member]
Liabilities		$ 1,914