Note 1 - Significant Accounting Policies and Concentrations of Risk (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

Available-for-sale Securities [Table Text Block]

	December 31, 2015
	Amortized Cost		Accrued Interest		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Obligations of U.S. Government and its agencies	$	26,557	$	88	$	—	$	(99	)	$	26,546
Corporate debt securities		21,820		184		—		(41	)		21,963
Certificates of deposit		21,884		21		5		(72	)		21,838
Total investments	$	70,261	$	293	$	5	$	(212	)	$	70,347

	December 31, 2014
	Amortized Cost		Accrued Interest		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Obligations of U.S. Government and its agencies	$	20,307	$	22	$	—	$	(23	)	$	20,306
Corporate debt securities		27,152		151		5		(47	)		27,261
Commercial paper		11,838		6		—		(63	)		11,781
Total investments	$	59,297	$	179	$	5	$	(133	)	$	59,348

Available For Sale Securities Debt Maturities Fair Value [Table Text Block]

	2015		2014
Maturing in one year or less	$	22,664	$	18,232
Maturing after one year through two years		28,395		25,459
Maturing after two years		19,288		15,657
Total investments	$	70,347	$	59,348

Schedule of Receivables from Collaborations [Table Text Block]

	December 31, 2015
	Billed		Unbilled		Total
U.S. Department of Health and Human Services	$	—	$	5,536	$	5,536
Shionogi & Co. Ltd.		469		—		469
Seqirus UK Limited		210		28		238
Total receivables	$	679	$	5,564	$	6,243

	December 31, 2014
	Billed		Unbilled		Total
U.S. Department of Health and Human Services	$	—	$	2,778	$	2,778
Shionogi & Co. Ltd.		1,071		—		1,071
Total receivables	$	1,071	$	2,778	$	3,849

Schedule of Inventory, Current [Table Text Block]

	As of December 31,
	2015		2014
Work in process	$	1,612	$	267
Finished goods		—		416
Net inventories	$	1,612	$	683

Schedule of Accrued Liabilities [Table Text Block]

	December 31,
	2015		2014
Compensation and benefits	$	424	$	2,105
Development costs		10,398		4,232
Inventory		549		397
Professional fees		242		238
Duties and taxes		102		75
Other		4,522		4,282
Total accrued expenses	$	16,237	$	11,329

Schedule of Revenues from Collaborations [Table Text Block]

	2015		2014		2013
Product sales, net	$	6,291	$	33	$	—
Royalty revenue		2,386		3,025		2,562
Collaborative and other research and development revenues:
U.S. Department of Health and Human Services		16,337		9,366		13,585
Green Cross Corporation		132		—		—
Shionogi (Japan)		1,184		1,184		1,184
Seqirus UK Limited		21,927		—		—
Total collaborative and other research and development revenues		39,580		10,550		14,769
Total revenues	$	48,257	$	13,608	$	17,331