MARKETABLE DEBT SECURITIES

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

MARKETABLE DEBT SECURITIES

MARKETABLE DEBT SECURITIES

We invest our excess cash balances in marketable debt securities and at each balance sheet date presented, we classify all of our investments in debt securities as available-for-sale and as current assets as they represent the investment of funds available for current operations. We did not record any impairment charges related to our marketable debt securities during the three and nine months ended September 30, 2020 or 2019.

The following tables summarize our marketable debt securities:

	As of September 30, 2020
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate notes	$	32,064	$	23	$	—	$	32,087
U.S. government-sponsored enterprise securities	253,014		171		(241)		252,944
U.S. treasury securities	1,008,972		1,011		(59)		1,009,924
Total	$	1,294,050	$	1,205	$	(300)	$	1,294,955

	As of December 31, 2019
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Certificates of deposit	$	4,303	$	—	$	(2)	$	4,301
Commercial paper	39,913		—		—		39,913
Corporate notes	146,016		58		(34)		146,040
U.S. government-sponsored enterprise securities	32,487		3		(2)		32,488
U.S. treasury securities	1,092,293		185		(71)		1,092,407
Total	$	1,315,012	$	246	$	(109)	$	1,315,149

The fair values of our marketable debt securities by classification in the condensed consolidated balance sheets were as follows:

(In thousands)	As of September 30, 2020		As of December 31, 2019
Cash and cash equivalents	$	15,000	$	340,132
Marketable debt securities	1,279,955		975,017
Total	$	1,294,955	$	1,315,149