CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS

Cash equivalents consist of instruments with remaining maturities of three months or less at the date of purchase. We classify all of our cash equivalents and short-term investments as “available-for-sale.” In general, these investments are free of trading restrictions. We carry these investments at fair value, based on quoted market prices or other readily available market information. Unrealized gains and losses, net of taxes, are included in accumulated other comprehensive income, which is reflected as a separate component of stockholders’ equity in our condensed consolidated balance sheets. Gains and losses are recognized when realized in our condensed consolidated statements of income. 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 income. Gains and losses are determined using the specific identification method.

Cash, cash equivalents and short-term investments consisted of the following as of March 2, 2018 (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Current assets:
Cash	$	336,972	$	—	$	—		$	336,972
Cash equivalents:
Money market mutual funds	2,322,247		—		—			2,322,247
Time deposits	7,762		—		—			7,762
Total cash equivalents	2,330,009		—		—			2,330,009
Total cash and cash equivalents	2,666,981		—		—			2,666,981
Short-term fixed income securities:
Asset-backed securities	92,067		—		(810		)	91,257
Corporate debt securities	2,461,348		797		(29,828		)	2,432,317
Foreign government securities	3,852		—		(55		)	3,797
Municipal securities	19,249		—		(268		)	18,981
U.S. Treasury securities	939,016		7		(4,386		)	934,637
Total short-term investments	3,515,532		804		(35,347		)	3,480,989
Total cash, cash equivalents and short-term investments	$	6,182,513	$	804	$	(35,347	)	$	6,147,970

Cash, cash equivalents and short-term investments consisted of the following as of December 1, 2017 (in thousands):



	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Current assets:
Cash	$	280,488	$	—	$	—		$	280,488
Cash equivalents:
Money market mutual funds	2,006,741		—		—			2,006,741
Time deposits	18,843		—		—			18,843
Total cash equivalents	2,025,584		—		—			2,025,584
Total cash and cash equivalents	2,306,072		—		—			2,306,072
Short-term fixed income securities:
Asset-backed securities	98,403		1		(403		)	98,001
Corporate debt securities	2,461,691		2,694		(10,125		)	2,454,260
Foreign government securities	2,396		—		(8		)	2,388
Municipal securities	21,189		8		(132		)	21,065
U.S. Treasury securities	941,538		2		(3,552		)	937,988
Total short-term investments	3,525,217		2,705		(14,220		)	3,513,702
Total cash, cash equivalents and short-term investments	$	5,831,289	$	2,705	$	(14,220	)	$	5,819,774

See Note 4 for further information regarding the fair value of our financial instruments.

The following table summarizes the fair value and gross unrealized losses related to available-for-sale securities, aggregated by investment category, that have been in an unrealized loss position for less than twelve months, as of March 2, 2018 and December 1, 2017 (in thousands):



	2018					2017
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate debt securities	$	1,811,370	$	(22,326	)	$	1,338,232	$	(5,459	)
Asset-backed securities	57,439		(495		)	64,618		(193		)
Municipal securities	18,389		(246		)	11,805		(115		)
Foreign government securities	3,796		(55		)	2,388		(8		)
U.S. Treasury securities	592,296		(3,050		)	593,296		(2,087		)
Total	$	2,483,290	$	(26,172	)	$	2,010,339	$	(7,862	)

There were 1,237 securities and 894 securities in an unrealized loss position for less than twelve months at March 2, 2018 and at December 1, 2017, respectively.

The following table summarizes the fair value and gross unrealized losses related to available-for-sale securities, aggregated by investment category, that were in a continuous unrealized loss position for more than twelve months, as of March 2, 2018 and December 1, 2017 (in thousands):



	2018					2017
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate debt securities	$	479,654	$	(7,502	)	$	500,689	$	(4,666	)
Asset-backed securities	33,818		(315		)	32,383		(210		)
Municipal securities	592		(22		)	598		(17		)
U.S. Treasury securities	299,842		(1,336		)	338,950		(1,465		)
Total	$	813,906	$	(9,175	)	$	872,620	$	(6,358	)

There were 342 securities and 360 securities in an unrealized loss position for more than twelve months at March 2, 2018 and at December 1, 2017, respectively.

The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated effective maturities as of March 2, 2018 (in thousands):



	Amortized Cost		Estimated Fair Value
Due within one year	$	1,210,398	$	1,205,298
Due between one and two years	1,099,330		1,088,663
Due between two and three years	856,020		844,181
Due after three years	349,784		342,847
Total	$	3,515,532	$	3,480,989

We review our debt securities classified as short-term investments on a regular basis to evaluate whether or not any security has experienced an other-than-temporary decline in fair value. We consider factors such as the length of time and extent to which the market value has been less than the cost, the financial condition and near-term prospects of the issuer and our intent to sell, or whether it is more likely than not we will be required to sell the investment before recovery of the investment’s amortized cost basis. If we believe that an other-than-temporary decline exists in one of these securities, we write down these investments to fair value. The portion of the write-down related to credit loss would be recorded to interest and other income, net in our condensed consolidated statements of income. Any portion not related to credit loss would be recorded to accumulated other comprehensive income, which is reflected as a separate component of stockholders’ equity in our condensed consolidated balance sheets. During the three months ended March 2, 2018 and March 3, 2017, we did not consider any of our investments to be other-than-temporarily impaired.