Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Taxes

Schedule of components of the income tax benefit

The components of the income tax benefit were as follow, in thousands:

	Year Ended December 31,
	2010		2011		2012
Current
Federal	$	—	$	14,090	$	—
State		—		2,155		—
Deferred
Federal		399		—		—
State		—		—		—
Total	$	399	$	16,245		—

Schedule of reconciliation of the expected income tax benefit computed using the federal statutory income tax rate to the entity's

A reconciliation of the expected income tax benefit computed using the federal statutory income tax rate to the Company's effective income tax rate is as follows, in thousands:

	Year Ended December 31,
	2010			2011			2012
Income tax (benefit) computed at federal statutory tax rate	$	(13,421	)	$	(13,419	)	$	(16,270	)
Permanent items		61			57			396
State taxes		(2,142	)		(2,155	)		(2,487	)
Change in valuation allowance		16,144			—			18,754
Uncertain tax position		190			129			(64)
Research and development credits		(1,267	)		(857	)		—
Other		36			—			(329)
Income tax benefit	$	(399	)	$	(16,245	)	$	—

Schedule of Significant components of the entity's deferred tax assets (liabilities)

The significant components of the Company's deferred tax assets (liabilities) were as follow, in thousands:

	As of December 31,
	2011			2012
Deferred tax assets:
Net operating loss carryforward	$	14,809		$	32,714
Deferred rent credit		514			477
Accrued compensation and non-qualified stock options		48			60
Deferred financing costs		35			—
Depreciation and amortization		98			282
Research and development credits		5,018			3,901
Other		9			788
Net deferred tax asset before valuation allowance		20,531			38,222
Valuation allowance		(20,531	)		(38,222	)
Net deferred tax asset	$	—		$	—

Schedule of reconciliation of the beginning and ending amount of gross unrecognized tax benefits

A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows, in thousands:

	Year Ended December 31,
	2010		2011		2012
Balance as of January 1	$	—	$	642	$	752
Gross increases related to prior-year tax positions		452		—		—
Gross increases (decrease) related to current-year tax positions		190		110		(64	)
Balance as of December 31	$	642	$	752	$	688