Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Taxes

Schedule of reconciliation of the statutory U.S. federal income tax rate to the entity's effective income tax rate

	Years Ended December 31,
	2012			2011			2010
Statutory U.S. federal tax rate		(34.0	)%		(34.0	)%		(34.0	)%
State taxes, net of federal benefit		4.2	%		(3.4	)%		(5.8	)%
Equity-based compensation expense		42.4	%		2.4	%		1.7	%
Permanent items, net		1.2	%		0.4	%		0.5	%
Tax credits		0.8	%		(1.6	)%		(2.2	)%
Valuation allowance		(19.5	)%		34.7	%		39.2	%
Total tax (benefit) expense		(4.9	)%		(1.5	)%		(0.6	)%

Schedule of components of the entity's deferred tax assets and liabilities

The components of our deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2012			2011
Assets
Net operating loss carryforwards	$	75,740		$	75,738
Tax credit carryforwards		12,403			12,560
Deferred revenue		22,315			19,321
Equity-based compensation expense		3,681			10,331
Capitalized research & development		45,137			43,463
Other		4,239			6,406
Property, Plant, and Equipment Depreciation		1,393			—
Liabilities
Property, Plant, and Equipment Depreciation		—			(130	)
		164,908			167,689
Valuation allowance		(164,908	)		(167,689	)
Net deferred taxes	$	—		$	—