Balance Sheet Account Details (Tables)

9 Months Ended

Sep. 30, 2012

Balance Sheet Account Details [Abstract]

Summary of short-term investments

	September 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-sale securities:
Commercial paper	$	36,659	$	1	$	(12	)	$	36,648
Corporate notes and bonds		100,806		30		(22	)		100,814
U.S. government agency securities		2,022		1		—			2,023
Total available-for-sale securities	$	139,487	$	32	$	(34	)	$	139,485

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Fair values and the gross unrealized losses of available-for-sale securities aggregated by investment category

	September 30, 2012
	Fair Value		Gross Unrealized Losses
Commercial paper	$	34,908	$	(12	)
Corporate notes and bonds		65,782		(22	)
Total	$	100,690	$	(34	)

Schedule of property and equipment, net

	September 30, 2012			December 31, 2011
Computer equipment and software	$	41,919		$	16,586
Furniture and fixtures		3,017			1,755
Leasehold improvements		815			2,795
Construction in progress		4,955			3,740
		50,706			24,876
Less: accumulated depreciation		(11,620	)		(4,181	)
Total property and equipment, net	$	39,086		$	20,695

Accrued expenses and other current liabilities

	September 30, 2012		December 31, 2011
Taxes payable	$	3,376	$	7,399
Bonuses and commissions		6,710		6,080
Accrued compensation		5,895		3,570
Accrued third-party professional services		2,141		1,919
Other employee expenses		5,447		1,809
Current portion of facility exit obligation		597		—
Other		7,872		4,831
Total accrued expenses and other current liabilities	$	32,038	$	25,608