Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2019

Debt Securities, Available-for-sale [Abstract]

Cash equivalents and marketable securities classified as available-for-sale

All cash equivalents and marketable securities are classified as available-for-sale. Total cash, cash equivalents and marketable securities are summarized as follows:

	As of September 30, 2019
(In thousands)	Fair Value		Amortized  Cost		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Weighted  Rate of  Return
Money market funds	$	12,639	$	12,639	$	—	$	—		1.81	%
U.S. Government bonds and notes	26,136		26,134		2		—			2.02	%
Corporate notes, bonds, commercial paper and other	259,319		259,330		51		(62		)	2.09	%
Total cash equivalents and marketable securities	298,094		298,103		53		(62		)
Cash	39,930		39,930		—		—
Total cash, cash equivalents and marketable securities	$	338,024	$	338,033	$	53	$	(62	)

	As of December 31, 2018
(In thousands)	Fair Value		Amortized  Cost		Gross  Unrealized  Gains		Gross  Unrealized  Losses			Weighted  Rate of  Return
Money market funds	$	10,080	$	10,080	$	—	$	—		2.23	%
U.S. Government bonds and notes	32,630		32,634		—		(4		)	2.28	%
Corporate notes, bonds, commercial paper and other	183,998		184,095		—		(97		)	2.37	%
Total cash equivalents and marketable securities	226,708		226,809		—		(101		)
Cash	51,056		51,056		—		—
Total cash, cash equivalents and marketable securities	$	277,764	$	277,865	$	—	$	(101	)

Available-for-sale securities reported at fair value

Available-for-sale securities are reported at fair value on the balance sheets and classified as follows:

	As of
(In thousands)	September 30, 2019		December 31, 2018
Cash equivalents	$	51,908	$	64,868
Short term marketable securities	246,186		161,840
Total cash equivalents and marketable securities	298,094		226,708
Cash	39,930		51,056
Total cash, cash equivalents and marketable securities	$	338,024	$	277,764

Estimated fair value of cash equivalents and marketable securities classified by the length of time that the securities have been in a continuous unrealized loss position

The estimated fair value of cash equivalents and marketable securities classified by the length of time that the securities have been in a continuous unrealized loss position at September 30, 2019 and December 31, 2018 are as follows:

	Fair Value				Gross Unrealized Loss
(In thousands)	September 30, 2019		December 31, 2018		September 30, 2019			December 31, 2018
Less than one year
U.S. Government bonds and notes	$	—	$	32,630	$	—		$	(4	)
Corporate notes, bonds and commercial paper	187,667		183,998		(62		)	(97		)
Total Corporate notes, bonds, and commercial paper and U.S. Government bonds and notes	$	187,667	$	216,628	$	(62	)	$	(101	)