Cash, Cash Equivalents and Marketable Securities

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents and Marketable Securities

Cash, Cash Equivalents and Marketable Securities 

The following table summarizes the amortized cost and fair value of the Company’s cash, cash equivalents and marketable securities as of December 31, 2018 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Current assets:
Cash and cash equivalents:
Cash	$	5,222	$	—	$	—	$	5,222
Money market funds	63,232		—		—		63,232
Total cash and cash equivalents	$	68,454	$	—	$	—	$	68,454
Marketable securities:
Commercial paper	$	152,940	$	—	$	—	$	152,940
Corporate debt securities	60,622		58		(75)		60,605
Certificates of deposit	128,647		—		—		128,647
U.S. Treasuries	103,521		31		(11)		103,541
Total marketable securities	$	445,730	$	89	$	(86)	$	445,733
Total cash, cash equivalents and marketable securities	$	514,184	$	89	$	(86)	$	514,187

The following table summarizes the amortized cost and fair value of marketable securities based on stated effective maturities as of December 31, 2018 (in thousands):

	Amortized Cost		Fair Value
Due within one year	$	408,479	$	408,471
Due between one and two years	37,251		37,262
Total	$	445,730	$	445,733

As of December 31, 2017, cash and cash equivalents included $289.8 million of money market fund investments having a carrying value equaled to their fair value. The Company did not hold any marketable securities at December 31, 2017.

There have been no significant realized gains or losses on available-for-sale securities for the periods presented. Available-for-sale debt securities that were in a continuous loss position but were not deemed to be other than temporarily impaired were immaterial at December 31, 2018.

See Note 5 for further information regarding the fair value of the Company’s financial instruments.