MARKETABLE SECURITIES (Tables)

6 Months Ended

Jun. 30, 2020

Cash and Cash Equivalents [Abstract]

Schedule of Cash and Cash Equivalents

The following table sets forth the Company’s cash, cash equivalents, restricted cash, and marketable securities at June 30, 2020 and December 31, 2019:

(In thousands)	June 30, 2020		December 31, 2019
Cash, cash equivalents, and restricted cash
Cash and money market	$	457,019	$	146,932
Cash equivalents	246,907		30,322
Restricted cash (1)	282		274
Total cash, cash equivalents, and restricted cash	704,208		177,528
Marketable securities
Available-for-sale debt securities	517,346		144,685
Equity securities	1,385		1,716
Total marketable securities	518,731		146,401
Total cash and cash equivalents, restricted cash and marketable securities	$	1,222,939	$	323,929

______________

(1)Restricted cash is included in other long-term assets on the condensed consolidated balance sheets. There was no restricted cash at June 30, 2019.

Schedule of restricted cash and cash equivalents

The following table sets forth the Company’s cash, cash equivalents, restricted cash, and marketable securities at June 30, 2020 and December 31, 2019:

(In thousands)	June 30, 2020		December 31, 2019
Cash, cash equivalents, and restricted cash
Cash and money market	$	457,019	$	146,932
Cash equivalents	246,907		30,322
Restricted cash (1)	282		274
Total cash, cash equivalents, and restricted cash	704,208		177,528
Marketable securities
Available-for-sale debt securities	517,346		144,685
Equity securities	1,385		1,716
Total marketable securities	518,731		146,401
Total cash and cash equivalents, restricted cash and marketable securities	$	1,222,939	$	323,929

______________

(1)Restricted cash is included in other long-term assets on the condensed consolidated balance sheets. There was no restricted cash at June 30, 2019.

Schedule of available-for-sale securities

Available-for-sale debt securities at June 30, 2020 consisted of the following:

​	June 30, 2020
(In thousands)	Amortized Cost		Gains in Accumulated Other Comprehensive Income (Loss)		Losses in Accumulated Other Comprehensive Income (Loss)		Estimated Fair Value
Cash equivalents	​		​		​		​
U.S. government agency securities	$	246,905	$	4	$	(2)	$	246,907
Total cash equivalents	246,905		4		(2)		246,907
Marketable securities
Corporate bonds	219,264		1,297		—		220,561
U.S. government agency securities	256,425		102		(1)		256,526
Certificates of deposit	10,000		—		—		10,000
Asset backed securities	22,174		85		—		22,259
Commercial paper	7,996		4		—		8,000
Total marketable securities	515,859		1,488		(1)		517,346
Total available-for-sale securities	$	762,764	$	1,492	$	(3)	$	764,253

Available-for-sale debt securities at December 31, 2019 consisted of the following:

​	December 31, 2019
(In thousands)	Amortized Cost		Gains in Accumulated Other Comprehensive Income (Loss)		Losses in Accumulated Other Comprehensive Income (Loss)		Estimated Fair Value
Cash equivalents	​		​		​		​
U.S. government agency securities	$	30,320	$	2	$	—	$	30,322
Total cash equivalents	30,320		2		—		30,322
Marketable securities
U.S. government agency securities	140,745		10		(73)		140,682
Corporate bonds	4,017		—		(14)		4,003
Total marketable securities	144,762		10		(87)		144,685
Total available-for-sale securities	$	175,082	$	12	$	(87)	$	175,007

Schedule of contractual maturities of available-for-sale investments

The following table summarizes contractual underlying maturities of the Company’s available-for-sale debt securities at June 30, 2020:​

​	Due one year or less				Due after one year through four years
(In thousands)	Cost		Fair Value		Cost		Fair Value
Cash equivalents	​		​		​		​
U.S. government agency securities	$	246,905	$	246,907	$	—	$	—
Total cash equivalents	246,905		246,907		—		—
Marketable securities
U.S. government agency securities	249,239		249,295		7,186		7,231
Corporate bonds	162,241		162,992		57,023		57,569
Certificates of deposit	10,000		10,000		—		—
Commercial paper	7,996		8,000		—		—
Asset backed securities	2,390		2,393		19,784		19,866
Total marketable securities	431,866		432,680		83,993		84,666
Total	$	678,771	$	679,587	$	83,993	$	84,666

Schedule of gross unrealized losses and fair values of investments in an unrealized loss position

The following table summarizes the gross unrealized losses and fair values of available-for-sale debt securities in an unrealized loss position as of June 30, 2020, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

​	Less than one year				One year or greater				Total
(In thousands)	Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
Cash equivalents
U.S. government agency securities	$	81,934	$	(2)	$	—	$	—	$	81,934	$	(2)
Total cash equivalents	81,934		(2)		—		—		81,934		(2)
Marketable securities
U.S. government agency securities	99,975		(1)		—		—		99,975		(1)
Total marketable securities	99,975		(1)		—		—		99,975		(1)
Total available-for-sale securities	$	181,909	$	(3)	$	—	$	—	$	181,909	$	(3)