Summary of Business and Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2012

Summary of Business and Significant Accounting Policies [Abstract]

Property and equipment estimated useful lives

Computer equipment and software	3-5 years
Furniture and fixtures	3-5 years
Leasehold improvements	Shorter of the lease term or estimated useful life

Fair value of stock option grant and stock purchase right granted under ESPP estimated on date of grant using Black-Scholes option pricing model

The following is a summary of short-term investments at June 30, 2012 (in thousands):

	June 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair  Value
Available-for-sale securities:
Commercial paper	$	5,993	$	4	$	(1	)	$	5,996
Corporate notes and bonds		14,781		3		(8	)		14,776
U.S. government agency securities		2,023		—		—			2,023
Total available-for-sale securities	$	22,797	$	7	$	(9	)	$	22,795