Note 10 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
United States	$	(60,313	)	$	(71,978	)	$	(77,649	)
Foreign		(12,202	)		(31,984	)		(18,431	)
Total	$	(72,515	)	$	(103,962	)	$	(96,080	)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Current:
U.S. Federal	$	—		$	—		$	96
U.S. State		(11	)		42			51
Foreign		70			375			1,105
		59			417			1,252
Deferred:
U.S. Federal		—			(6,734	)		(11,312	)
U.S. State		—			—			(613	)
Foreign		337			(1,894	)		(10,503	)
		337			(8,628	)		(22,428	)
Total	$	396		$	(8,211	)	$	(21,176	)

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Benefit at statutory rate	$	(15,228	)	$	(21,832	)	$	(32,562	)
State income taxes		(587	)		594			(585	)
Research and development credits		(16,933	)		(13,283	)		(12,983	)
Change in valuation allowance		31,917			13,757			40,028
Impact of foreign operations		(1,045	)		5,925			(1,951	)
Unrecognized tax benefits		6,725			5,340			3,596
Stock-based compensation		(4,731	)		(381	)		(10,248	)
Prior year return to provision adjustment		(1,167	)		1,422			1,105
Section 162(m)		1,046			—			—
Effect of U. S. tax law change		—			—			(4,602	)
Impairment of intangibles		—			—			(2,328	)
Other		399			247			(646	)
	$	396		$	(8,211	)	$	(21,176	)

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2019			2018
Deferred tax assets
Net operating loss carry forwards	$	48,481		$	39,888
Research and development credits		84,268			69,320
Stock-based compensation		8,884			9,055
Accrued expenses and allowances		1,897			2,334
Amortization and depreciation		—			1,408
Operating lease liability		7,345			—
Other temporary differences		6,884			6,411
Foreign tax credit		2,338			2,338
Valuation allowance		(123,989	)		(92,315	)
Total deferred tax assets		36,108			38,439
Deferred tax liabilities
Acquired intangible assets		(16,092	)		(22,593	)
Convertible debt		(6,444	)		(11,596	)
Amortization and depreciation		(2,123	)		—
Right of use asset		(6,806	)		—
Other deferred tax liabilities		(1,482	)		(603	)
Total deferred tax liabilities		(32,947	)		(34,792	)
Deferred tax assets, net	$	3,161		$	3,647

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	Year Ended December 31,
	2019			2018			2017
Balance as of January 1	$	53,943		$	47,606		$	56,503
Increases based on tax positions related to the current year		7,926			5,747			4,656
Increases (decreases) based on tax positions of prior year		(518	)		708			(13,452	)
Statute of limitation expirations		(51	)		(118	)		(101	)
Balance as of December 31	$	61,300		$	53,943		$	47,606