4. Cash Equivalents and Investments

As of September 30, 2013, and December 31, 2012, we had invested our excess cash balances primarily in money market funds, certificates of deposit, corporate securities and corporate debt securities. Our securities are classified as available-for-sale and are carried at estimated fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss) in stockholders’ equity (deficit), net of estimated taxes. The cost of securities sold is based on the specific identification method. To date, we have not experienced credit losses on investments in these instruments and we do not require collateral for our investment activities.



Summary of Cash and Available-For-Sale Securities	Adjusted Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value		Cash and Cash Equivalents		Restricted Investment		Short-Term Marketable Securities
(In thousands)
September 30, 2013
Cash	$	49,790	$	—	$	—	$	49,790	$	49,790	$	—	$	—
Money market funds	269,806		—		—		269,806		269,806		—		—
Certificates of deposit	1,682		—		—		1,682		—		—		1,682
Corporate securities	3,500		1,680		—		5,180		—		—		5,180
Total	$	324,778	$	1,680	$	—	$	326,458	$	319,596	$	—	$	6,862

December 31, 2012
Cash	$	7,894	$	—	$	—	$	7,894	$	7,894	$	—	$	—
Money market funds	121,095		—		—		121,095		121,095		—		—
Certificates of deposit	26,128		—		—		26,128		2,223		20,000		3,905
Corporate debt securities	13,562		10		—		13,572		—		—		13,572
Total	$	168,679	$	10	$	—	$	168,689	$	131,212	$	20,000	$	17,477

No gains or losses on sales of available-for-sale securities were recognized for the three and nine months ended September 30, 2013 and 2012.



Cash and Available-For-Sale Securities by Contractual Maturity	September 30, 2013				December 31, 2012
(In thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	324,778	$	326,458	$	168,679	$	168,689
Greater than one year but less than five years	—		—		—		—
Total	$	324,778	$	326,458	$	168,679	$	168,689

No significant facts or circumstances have arisen to indicate that there has been any deterioration in the creditworthiness of the issuers of these securities. Based on our review of these securities, we believe that we had no other-than-temporary impairments on these securities as of September 30, 2013, and December 31, 2012.