Cash, Cash Equivalents and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2013

Summary of Cash, Cash Equivalents and Marketable Securities Available-for-sale

The following is a summary of cash, cash equivalents and marketable securities available-for-sale as of March 31, 2013 and December 31, 2012 (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
March 31, 2013
Cash and cash equivalents:
Cash	$	2,567	$	—	$	—		$	2,567
Money market funds		18,783		—		—			18,783
U.S. government agency securities		2,201		—		—			2,201
U.S. treasury securities		750							750
Municipal securities		715		—		—			715
Total cash and cash equivalents		25,016		—		—			25,016
Marketable securities available-for-sale:
U.S. government agency securities		77,821		36		—			77,857
U.S. treasury securities		2,499		1		—			2,500
Total marketable securities available-for-sale		80,320		37		—			80,357
Total cash, cash equivalents and marketable securities	$	105,336	$	37	$	—		$	105,373
December 31, 2012
Cash and cash equivalents:
Cash	$	1,542	$	—	$	—		$	1,542
Money market funds		3,140		—		—			3,140
U.S. government agency securities		2,202		—		—			2,202
Municipal securities		715		—		—			715
Total cash and cash equivalents		7,599		—		—			7,599
Marketable securities available-for-sale:
U.S. government agency securities		116,986		46		(1	)		117,031
U.S. treasury securities		500		—		—			500
Total marketable securities available-for-sale		117,486		46		(1	)		117,531
Total cash, cash equivalents and marketable securities	$	125,085	$	46	$	(1	)	$	125,130

Summary of Amortized Cost and Estimated Fair Value of Marketable Securities Available-for-sale

The following is a summary of the amortized cost and estimated fair value of marketable securities available-for-sale at March 31, 2013, by contractual maturity (in thousands):

	March 31, 2013
	Amortized Cost		Estimated Fair Value
Mature in one year or less	$	61,367	$	61,393
Mature after one year through two years		18,953		18,964
	$	80,320	$	80,357