Investments and Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2012

Investments and Fair Value Measurement [Abstract]

Schedule of available-for-sale securities

The table below summarizes the Company’s available-for-sale securities (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
December 31, 2012
Cash equivalents:
U.S. government sponsored entity debt securities	$	2,997	$	—	$	—		$	2,997
Money market funds		15,839		—		—			15,839
Total		18,836		—		—			18,836
Marketable securities:
U.S. government sponsored entity debt securities		54,426		26		—			54,452
Total		54,426		26		—			54,452
Total cash equivalents and marketable securities	$	73,262	$	26	$	—		$	73,288
December 31, 2011
Cash equivalents:
Money market funds	$	15,258		—		—		$	15,258
Total		15,258		—		—			15,258
Marketable securities:
U.S. government sponsored entity debt securities		27,020		—		(7	)		27,013
U.S. treasury debt securities		751		1		—			752
Corporate debt securities		39,583		18		—			39,601
Total		67,354		19		(7	)		67,366
Total cash equivalents and marketable securities	$	82,612	$	19	$	(7	)	$	82,624

Summary of fair value measurements of cash equivalents and available-for-sale marketable securities

The fair value measurements of cash equivalents and available-for-sale marketable securities are identified at the following levels within the fair value hierarchy (in thousands):

	December 31, 2012 Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
U.S. government sponsored entity debt securities	$	2,997	$	—	$	2,997	$	—
Money market funds		15,839		15,839		—		—
Total		18,836		15,839		2,997		—
Marketable securities:
U.S. government sponsored entity debt securities		54,452		—		54,452		—
Total		54,452		—		54,452		—
Total cash equivalents and marketable securities	$	73,288	$	15,839	$	57,449	$	—

	December 31, 2011 Fair Value Measurements
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	15,258	$	15,258	$	—	$	—
Total		15,258		15,258		—		—
Marketable securities:
U.S. government sponsored entity debt securities		27,013		—		27,013		—
U.S. treasury debt securities		752		—		752		—
Corporate debt securities		39,601		—		39,601		—
Total		67,366		—		67,366		—
Total cash equivalents and marketable securities	$	82,624	$	15,258	$	67,366	$	—