4. Cash Equivalents and Investments

As of March 31, 2015, and December 31, 2014, we had invested our excess cash balances primarily in money market funds, and a corporate equity security. 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 gain" in stockholders’ equity, net of estimated taxes. See Note 3 for fair value measurement information. 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		Short-Term Investments
(In thousands)
March 31, 2015
Cash	$	225,832	$	—	$	—	$	225,832	$	225,832	$	—
Money market funds	190,836		—		—		190,836		190,836		—
Corporate securities	1,750		502		—		2,252		—		2,252
Total	$	418,418	$	502	$	—	$	418,920	$	416,668	$	2,252

December 31, 2014
Cash	$	69,585	$	—	$	—	$	69,585	$	69,585	$	—
Money market funds	221,792		—		—		221,792		221,792		—
Corporate securities	1,750		560		—		2,310		—		2,310
Total	$	293,127	$	560	$	—	$	293,687	$	291,377	$	2,310

No gains or losses on sales of available-for-sale securities were recognized for the three months ended March 31, 2015 and 2014.

The unrealized gain (loss) on investments included in "Other comprehensive income (loss), net of tax" was approximately $326,000 and $364,000 as of March 31, 2015, and December 31, 2014, respectively.