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. Short-term investments are classified as current assets, even though maturities may extend beyond one year, because they represent investments of cash available for operations. We classify all 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 (loss) 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 six months ended December 31, 2017 and 2016.

Cash, cash equivalents and short-term investments consisted of the following as of December 31, 2017 (in thousands):



Description	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash	$	11,329	$	—	$	—		$	11,329
Cash equivalents:
Money market mutual funds	631		—		—			631
Commercial paper	1,996		—		—			1,996
Total cash equivalents	2,627		—		—			2,627
Total cash and cash equivalents	13,956		—		—			13,956
Short-term investments:
U.S. treasury securities	2,985		—		(10		)	2,975
U.S. agency securities	3,051		—		(25		)	3,026
Asset-backed securities	9,476		2		(43		)	9,435
Municipal securities	5,522		1		(3		)	5,520
Commercial paper	3,735		—		(2		)	3,733
Corporate bonds	52,307		2		(225		)	52,084
Total short-term investments	77,076		5		(308		)	76,773
Cash, cash equivalents and short-term investments	$	91,032	$	5	$	(308	)	$	90,729

Cash, cash equivalents and short-term investments consisted of the following as of June 30, 2017 (in thousands):



Description	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash	$	17,316	$	—	$	—		$	17,316
Cash equivalents:
Money market mutual funds	444		—		—			444
Commercial paper	2,997		—		—			2,997
Total cash equivalents	3,441		—		—			3,441
Total cash and cash equivalents	20,757		—		—			20,757
Short-term investments:
U.S. treasury securities	1,476		—		(3		)	1,473
U.S. agency securities	2,553		—		(16		)	2,537
Asset-backed securities	9,707		8		(10		)	9,705
Municipal securities	7,980		3		(1		)	7,982
Commercial paper	4,240		—		(1		)	4,239
Foreign government securities	750		—		—			750
Corporate bonds	50,987		24		(99		)	50,912
Total short-term investments	77,693		35		(130		)	77,598
Cash, cash equivalents and short-term investments	$	98,450	$	35	$	(130	)	$	98,355

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 December 31, 2017 (in thousands):



	Amortized Cost		Estimated Fair Value
Due within one year	$	32,846	$	32,801
Due between one and two years	28,308		28,156
Due between two and three years	15,922		15,816
Total	$	77,076	$	76,773

Declines in fair value judged to be other-than-temporary on securities available for sale are included as a component of other income (expense), 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 December 31, 2017, we did not consider any of our investments to be other-than-temporarily impaired.