4. Cash Equivalents and Short-Term Investments

As of September 30, 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 income" 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)
September 30, 2015
Cash	$	88,005	$	—	$	—	$	88,005	$	88,005	$	—
Money market funds	139,850		—		—		139,850		139,850		—
Corporate securities	1,206		621		—		1,827		—		1,827
Total	$	229,061	$	621	$	—	$	229,682	$	227,855	$	1,827

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

For the three and nine months ended September 30, 2015, recognized realized gains of available-for-sale securities was $580,000. There were no gains or losses on sales of available-for-sale securities recognized for the three and nine months ended September 31, 2014.

The unrealized gains on investments included in "Other comprehensive income (loss), net of tax" was approximately $404,000 and $364,000 as of September 30, 2015, and December 31, 2014, respectively.