Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2012

Significant Accounting Policies [Abstract]

Fair value of the Company's investments by type

	June 30, 2012
					Gross		Gross
	Amortized		Accrued		Unrealized		Unrealized			Estimated
	Cost		Interest		Gains		Losses			Fair Value
U.S. Treasury securities	$	1,999	$	2	$	7	$	—		$	2,008
Obligations of U.S. government and its agencies		10,213		12		—		(3	)		10,222
Corporate debt securities		6,872		34		15		—			6,921
Commercial paper		1,399		—		—		—			1,399
Certificate of deposit		800		—		—		—			800
Municipal obligations		7,895		43		21		—			7,959
Total investments	$	29,178	$	91	$	43	$	(3	)	$	29,309

	December 31, 2011
					Gross		Gross
	Amortized		Accrued		Unrealized		Unrealized			Estimated
	Cost		Interest		Gains		Losses			Fair Value
U.S. Treasury securities	$	1,998	$	2	$	14	$	—		$	2,014
Obligations of U.S. government and its agencies		5,000		10		—		—			5,010
Corporate debt securities		10,924		80		15		(9	)		11,010
Commercial paper		10,939		—		2		(1	)		10,940
Asset-backed securities		611		—		—		—			611
Certificate of deposit		801		1		—		—			802
Municipal obligations		10,182		68		21		(2	)		10,269
Total investments	$	40,455	$	161	$	52	$	(12	)	$	40,656

Scheduled maturity for the Company's investments

Maturing in one year or less	$	12,958
Maturing after one year through two years		16,351
Total investments	$	29,309

Summary of receivables from collaborations

	Billed		Unbilled		Total
U.S. Department of Health and Human Services	$	681	$	4,403	$	5,084
Total receivables from collaborations	$	681	$	4,403	$	5,084

Components of inventories

	2012			2011
Supplies	$	263		$	898
Finished goods		3,980			3,980
Reserve for finished goods		(3,980	)		(4,615	)
Net inventories	$	263		$	263

Revenues from collaborations

	Three Months				Six Months
	2012		2011		2012		2011
Collaborative and other research and development revenues:
U.S. Department of Health and Human Services	$	3,914	$	3,111	$	8,073	$	7,772
Shionogi (Japan)		296		296		592		592
Mundipharma (United Kingdom)		—		328		7,766		720
Grants (United States)		—		—		—		86
Total revenues	$	4,210	$	3,735	$	16,431	$	9,170