2. Cash, Cash Equivalents, and Short-Term Investments

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents consist of cash on hand, highly liquid investments in commercial paper, money market funds, corporate debt obligations and various deposit accounts.

The Company considers all high quality investments purchased with original maturities at the date of purchase greater than three months to be short-term investments. Investments are available to be used for current operations and are, therefore, classified as current assets even though maturities may extend beyond one year. Cash equivalents and short-term investments are classified as available-for-sale and are, therefore, recorded at fair value on the condensed consolidated balance sheets, with any unrealized gains and losses reported in accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in its condensed consolidated balance sheets, until realized. The Company uses the specific-identification method to compute gains and losses on the investments. The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included as a component of other income (expense), net in the condensed consolidated statements of operations.

Cash, cash equivalents and short-term investments consist of the following (in thousands):

	As of September 30, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents:
Cash	$	76,134	$	-	$	-	$	76,134
Commercial paper		2,999		-				2,999
Money market funds		84,802		-		-		84,802
Total	$	163,935	$	-	$	-	$	163,935
Short-term investments:
Commercial paper	$	16,649	$	-	$	5	$	16,644
Corporate debt obligations		147,383		1		207		147,177
US government agencies		14,998		-		30		14,968
Bank deposits		480		-				480
Total	$	179,510	$	1	$	242	$	179,269

	As of December 31, 2016
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents:
Cash	$	63,642	$	-	$	-	$	63,642
Commercial paper		6,995		-		2		6,993
Money market funds		36,708		-		-		36,708
Total	$	107,345	$	-	$	2	$	107,343
Short-term investments:
Commercial paper	$	14,245	$	-	$	8	$	14,237
Corporate debt obligations		110,062		-		347		109,715
US government agencies		18,998		2		50		18,950
Bank deposits		10,846		1		-		10,847
Total	$	154,151	$	3	$	405	$	153,749

The following table summarizes the cost and estimated fair value of short-term investments based on stated effective maturities as of September 30, 2017 (in thousands):

	As of September 30, 2017
			Estimated
	Amortized		Fair
	Cost		Value
Short-term investments:
Due within one year	$	111,172	$	111,045
Due within two years		68,338		68,224
Total	$	179,510	$	179,269

The gross unrealized loss related to these securities was due primarily to changes in interest rates. The Company reviews its short-term investments on a regular basis to evaluate whether or not any security has experienced an other-than-temporary decline in fair value. The Company considers 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 its intent to sell, or whether it is more likely than not the Company will be required to sell, the investment before recovery of the investment’s amortized cost basis. If the Company believes that an other-than-temporary decline exists in one of these securities, the Company writes down these investments to fair value. For debt securities, the portion of the write-down related to credit loss would be recorded to other income (expense), net, in the Company’s condensed consolidated statements of operations. Any portion not related to credit loss would be recorded to accumulated other comprehensive income (loss), which is reflected as a separate component of stockholders’ equity in the Company’s condensed consolidated balance sheets. During the three and nine months ended September 30, 2017 and 2016, the Company did not consider any of its investments to be other-than-temporarily impaired.

The following tables show the short-term investments in an unrealized loss position and the related gross unrealized losses and fair value and length of time that the short-term investments have been in a continuous unrealized loss position (in thousands):

	As of September 30, 2017
	Less than 12 Months				12 Months or Greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Commercial paper	$	14,919	$	5	$	-	$	-	$	14,919	$	5
Corporate debt obligations		92,500		151		50,152		56		142,652	$	207
US government agencies		-		-		14,968		30		14,968		30
Bank deposits		480		-		-		-		480	$	-
	$	107,899	$	156	$	65,120	$	86	$	173,019	$	242

	As of December 31, 2016
	Less than 12 Months				12 Months or Greater				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Commercial paper	$	14,237	$	8	$	-	$	-	$	14,237	$	8
Corporate debt obligations		78,821		323		29,689		24		108,510	$	347
US government agencies		11,451		46		3,496		4		14,947		50
	$	104,509	$	377	$	33,185	$	28	$	137,694	$	405