Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2012

Investments, Debt and Equity Securities [Abstract]

The composition of our marketable securities

The composition of our marketable securities is as follows (in thousands):

	September 30,				December 31,
	2012				2011
	Cost		Fair Value		Cost		Fair Value
Commercial paper	$	748	$	748	$	2,395	$	2,395
Certificates of deposit	9,769		9,769		8,333		8,326
Corporate bonds/notes	10,927		10,926		7,534		7,523
Municipal bonds/notes	287		287		—		—
Agency bonds/notes	900		901		7,320		7,323
Total marketable securities	$	22,631	$	22,631	$	25,582	$	25,567

The maturities of our marketable securities available for sale

The maturities of our marketable securities available for sale as of September 30, 2012 are as follows:

	Earliest		Latest
Commercial paper	4/5/2013	to	4/5/2013
Certificates of deposit	10/14/2012	to	2/18/2014
Corporate bonds/notes	10/1/2012	to	1/15/2014
Municipal bonds/notes	9/1/2013	to	9/1/2013
Agency bonds/notes	7/1/2013	to	7/1/2013