Marketable Securities

6 Months Ended

Jun. 30, 2013

Marketable Securities [Abstract]

Marketable Securities

5. Marketable Securities

Our investments in marketable securities are made within the guidelines of our investment policy, which has established guidelines relative to the diversification of our investments and their maturities, with the principle objective of capital preservation, maintaining liquidity, and avoiding concentrations.

The following is a summary of available-for-sale securities as of June 30, 2013 and December 31, 2012 (in thousands):

As of June 30, 2013	Aggregate Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value
U.S. Treasury and agency securities	$	15,237	$	333	$	—	$	15,570
Non-U.S. government securities		5,097		—		(1)		5,096
Certificates of deposit		3,436		—		—		3,436
Corporate debt securities		19,731		0		(25)		19,706
Total	$	43,501	$	333	$	(26)	$	43,808
As of December 31, 2012	Aggregate Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value
U.S. Treasury and agency securities	$	17,706	$	20	$	0	$	17,726
Corporate debt securities		20,545		20		(2)		20,563
Municipal securities		170		—		0		170
Total	$	38,421	$	40	$	(2)	$	38,459

    As of June 30, 2013, $43.8 million ofmarketable securities had scheduled maturities of less than one year. In addition, more than half of our marketable securities were AA rated, and all securities had at least an A rating.

    Investments in money market and similar short-term investments are recorded on our consolidated balance sheets as cash and cash equivalents.

    Amounts reclassified out of accumulated other comprehensive income during the three and six month periods were not material.