Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2015

Summary of Significant Accounting Policies

Schedule of anti-dilutive shares

The following table presents anti-dilutive shares for the three and nine months ended September 30, 2015 and 2014 (in thousands):

	Three Months Ended September 30,		Nine Months Ended September 30,
	2015	2014	2015	2014
Weighted-average anti-dilutive shares related to:
Outstanding stock options	2,690	6,572	4,341	5,763
Restricted stock awards	457	822	547	860

Schedule of assets measured at fair value on a recurring basis

The tables below present information about the Company’s assets that are regularly measured and carried at fair value as of September 30, 2015 and December 31, 2014, and indicate the level within the fair value hierarchy of the valuation techniques utilized to determine such fair value (in thousands):

Description	Balance as of September 30, 2015		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds and overnight repurchase agreement	$	64,341	$	48,341	$	16,000	$	—
Marketable securities:
Corporate debt securities	102,034		—		102,034		—
Commercial paper obligations	145,345		—		145,345		—
Asset-backed securities	57,503		—		57,503		—
Total	$	369,223	$	48,341	$	320,882	$	—

Description	Balance as of December 31, 2014		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Unobservable Inputs (Level 3)
Assets:
Cash equivalents:
Money market funds	$	55,283	$	55,283	$	—	$	—
Corporate debt securities	980		—		980		—
Marketable securities:
Corporate debt securities	70,668		—		70,668		—
Commercial paper obligations	15,250		—		15,250		—
Foreign government bonds	18,520		—		18,520		—
Asset-backed securities	25,742		—		25,742		—
Total	$	186,443	$	55,283	$	131,160	$	—

Schedule of reconciliation of cash, cash equivalents and marketable securities from amortized cost to fair value

The following tables summarize the Company’s cash, cash equivalents and marketable securities as of September 30, 2015 and December 31, 2014 (in thousands):

As of September 30, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash, money market funds and overnight repurchase agreement	$	69,987	$	—	$	—		$	69,987
Corporate debt securities due in one year or less	102,148		3		(116		)	102,035
Commercial paper obligations due in one year or less	145,205		139		—			145,344
Asset-backed securities due in one year or less	57,513		2		(12		)	57,503
Total	$	374,853	$	144	$	(128	)	$	374,869
Reported as:
Cash and cash equivalents	$	69,987	$	—	$	—		$	69,987
Marketable securities	304,866		144		(128		)	304,882
Total	$	374,853	$	144	$	(128	)	$	374,869

As of December 31, 2014	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash and money market funds	$	60,369	$	—	$	—		$	60,369
Corporate debt securities due in one year or less	71,669		3		(24		)	71,648
Commercial paper obligations due in one year or less	15,237		13		—			15,250
Foreign government bonds due in one year or less	18,519		2		(1		)	18,520
Asset-backed securities due in one year or less	25,751		—		(9		)	25,742
Total	$	191,545	$	18	$	(34	)	$	191,529
Reported as:
Cash and cash equivalents	$	61,349	$	—	$	—		$	61,349
Marketable securities	130,196		18		(34		)	130,180
Total	$	191,545	$	18	$	(34	)	$	191,529

Schedule of aggregate fair value and unrealized losses on marketable securities

The following table summarizes the aggregate fair value of these securities at September 30, 2015 and December 31, 2014 (in thousands):

	As of September 30, 2015					As of December 31, 2014
	Aggregate Fair Value		Unrealized Losses			Aggregate Fair Value		Unrealized Losses
Corporate debt securities due in one year or less	$	89,793	$	(116	)	$	63,221	$	(24	)
Foreign government bonds due in one year or less	$	—	$	—		$	12,773	$	(1	)
Asset-backed securities due in one year or less	$	52,558	$	(12	)	$	25,742	$	(9	)

Summary of changes in accumulated other comprehensive income

The following tables summarize the changes in accumulated other comprehensive income (loss) during the three and nine months ended September 30, 2015 and 2014 (in thousands):

	Unrealized Gains (Losses) on Securities Available for Sale
Balance as of July 1, 2015	$	20
Other comprehensive loss before reclassifications	(4		)
Amounts reclassified from accumulated other comprehensive income (loss)	—
Net current period other comprehensive loss	(4		)
Balance as of September 30, 2015	$	16

	Unrealized Gains (Losses) on Securities Available for Sale
Balance as of January 1, 2015	$	(16	)
Other comprehensive income before reclassifications	32
Amounts reclassified from accumulated other comprehensive income (loss)	—
Net current period other comprehensive income	32
Balance as of September 30, 2015	$	16

	Unrealized Gains (Losses) on Securities Available for Sale
Balance as of July 1, 2014	$	46
Other comprehensive income before reclassifications	(26		)
Amounts reclassified from accumulated other comprehensive income (loss)	—
Net current period other comprehensive income	(26		)
Balance as of September 30, 2014	$	20

	Unrealized Gains (Losses) on Securities Available for Sale
Balance as of January 1, 2014	$	25
Other comprehensive income before reclassifications	(5		)
Amounts reclassified from accumulated other comprehensive income (loss)	—
Net current period other comprehensive income	(5		)
Balance as of September 30, 2014	$	20