Cash, cash equivalents and short-term investments

Cash and 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. Short-term investments consist of readily marketable securities with a remaining maturity of more than three months from the date of purchase. We classify all of our 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 we have determined 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. We had no material realized gains or losses in the three months ended September 30, 2013 and 2012.

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



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash	$	12,397	$	—	$	—		$	12,397
Cash equivalents:
Money market mutual funds	3,477		—		—			3,477
Total cash equivalents	3,477		—		—			3,477
Total cash and cash equivalents	15,874		—		—			15,874
Short-term securities:
Certificates of deposit	1,000		2		—			1,002
Municipal securities	141,648		318		(43		)	141,923
Commercial paper	3,393		3		—			3,396
Corporate bonds	19,267		65		(1		)	19,331
Total short-term investments	165,308		388		(44		)	165,652
Cash, cash equivalents and short-term investments	$	181,182	$	388	$	(44	)	$	181,526

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



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash	$	23,546	$	—	$	—		$	23,546
Cash equivalents:
Money market mutual funds	2,241		—		—			2,241
Total cash equivalents	2,241		—		—			2,241
Total cash and cash equivalents	25,787		—		—			25,787
Short-term investments:
Certificates of deposit	1,000		3		—			1,003
Municipal securities	148,888		242		(137		)	148,993
Commercial paper	3,389		2		—			3,391
Corporate bonds	12,462		58		(9		)	12,511
Total short-term investments	165,739		305		(146		)	165,898
Cash, cash equivalents and short-term investments	$	191,526	$	305	$	(146	)	$	191,685

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, 2013 (in thousands):



	Amortized Cost		Estimated Fair Value
Due within one year	$	72,091	$	72,204
Due within two years	70,333		70,542
Due after two years	22,884		22,906
Total	$	165,308	$	165,652

Declines in fair value judged to be other-than-temporary on securities available for sale are included as a component of other income, net. In order to determine whether a decline in value is other-than-temporary, we evaluate, among other factors: the duration and extent to which the fair value has been less than the carrying value and our intent and ability to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair market value. As of September 30, 2013, we did not consider any of our investments to be other-than-temporarily impaired.