NOTE 3—MARKETABLE SECURITIES

The Company classifies its marketable securities as available-for-sale and records its investments at estimated fair value based on quoted market prices or observable market inputs of substantially identical assets. Unrealized holding gains and losses are included in accumulated other comprehensive income (loss). Investments that have maturities beyond one year as of the end of the reporting period are classified as non-current.

The Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is judged to be other-than-temporary. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time and extent to which the fair value has been less than the Company’s cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. Realized gains and losses on available-for-sale securities are included in other income, which is determined using the specific identification method

The table below summarizes the Company’s investments (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		(Losses)			Fair Value
September 30, 2018
Cash equivalents:
Money market funds	$	18	$	—	$	—		$	18
Total		18		—		—			18
Available-for-sale securities:
Commercial paper securities		317,203		11		(95	)		317,119
Corporate debt securities		83,684		—		(105	)		83,579
U.S. government-sponsored entity debt securities		18,598		—		(24	)		18,574
Total		419,485		11		(224	)		419,272
Total cash equivalents and available-for-sale securities	$	419,503	$	11	$	(224	)	$	419,290
December 31, 2017
Cash equivalents:
Money market funds	$	24,290	$	—	$	—		$	24,290
Commercial paper securities		4,595		—		—			4,595
Total		28,885		—		—			28,885
Available-for-sale securities:
Commercial paper securities		110,365		—		(118	)		110,247
Corporate debt securities		75,886		—		(131	)		75,755
U.S. government-sponsored entity debt securities		8,498		—		(6	)		8,492
Total		194,749		—		(255	)		194,494
Total cash equivalents and available-for-sale securities	$	223,634		—	$	(255	)	$	223,379

The Company had no material realized losses or other-than-temporary impairments of its investments for the nine months ended September 30, 2018 and 2017. As of September 30, 2018, all of the Company’s investments had maturity dates within one year. The Company has the intent and ability to hold its investments for a period of time sufficient to allow for any anticipated recovery in market value.