Cash, cash equivalents and short-term investments

Cash equivalents consist of highly liquid fixed-income investments with original maturities of three months or less at the time of purchase, including money market funds. The Company has cash and cash equivalents held on its behalf by a third party of $0.7 million and $0.5 million as of September 30, 2014 and December 31, 2013, respectively. Short-term investments consist of readily marketable securities with a remaining maturity of more than three months from time of purchase. The Company classifies all of its cash equivalents and short-term investments as “available for sale,” as these investments are free of trading restrictions. These marketable securities are carried at fair value, with the unrealized gains and losses, net of tax, reported as accumulated other comprehensive income and included as a separate component of stockholders’ equity. Gains and losses are recognized when realized. When the Company determines that an other-than-temporary decline in fair value has occurred, the amount of the decline that is related to a credit loss is recognized in earnings. Gains and losses are determined using the specific identification method. The Company’s realized gains and losses in the three and nine months ended September 30, 2014 and 2013 were insignificant.

Cash and cash equivalents and short-term investments consisted of the following as of September 30, 2014 and December 31, 2013 (in thousands):

September 30, 2014



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Description
Cash	$	98,287	$	—	$	—		$	98,287
Cash equivalents:
Money market mutual funds	635		—		—			635
Total cash and cash equivalents	98,922		—		—			98,922
Short-term investments:
Corporate bonds	47,938		60		(54		)	47,944
U.S. agency securities	39,267		36		(26		)	39,277
Asset-backed securities	22,035		12		(39		)	22,008
U.S. Treasury securities	15,740		44		(12		)	15,772
Total short-term investments	124,980		152		(131		)	125,001
Cash, cash equivalents and short-term investments	$	223,902	$	152	$	(131	)	$	223,923

December 31, 2013



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Description
Cash	$	169,968	$	—	$	—		$	169,968
Cash equivalents:
Money market mutual funds	164		—		—			164
Total cash and cash equivalents	170,132		—		—			170,132
Short-term investments:
Corporate bonds	40,503		90		(10		)	40,583
U.S. agency securities	31,720		40		(13		)	31,747
Asset-backed securities	15,880		14		(12		)	15,882
U.S. Treasury securities	16,742		50		(3		)	16,789
Total short-term investments	104,845		194		(38		)	105,001
Cash, cash equivalents and short-term investments	$	274,977	$	194	$	(38	)	$	275,133

The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated maturities as of September 30, 2014:



	Amortized Cost		Estimated Fair Value
	(in thousands)
Less than 1 year	$	15,028	$	15,047
Due in 1 to 3 years	109,952		109,954
Total	$	124,980	$	125,001

As of September 30, 2014 and December 31, 2013, the Company did not consider any of its investments to be other-than-temporarily impaired.