Marketable Securities and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Marketable Securities

The following tables present details of the Company’s marketable securities as of December 31, 2019 and 2018:    

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Short-term:
Investment securities	$	404,294	$	20	$	(62	)	$	404,252
Long-term:
Investment securities	155,616		92		(18		)	155,690
Total	$	559,910	$	112	$	(80	)	$	559,942

        

	December 31, 2018
	Amortized Cost		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Short-term:
Investment securities	$	114,402	$	(124	)	$	114,278
Long-term:
Investment securities	6,603		(77		)	6,526
Total	$	121,005	$	(201	)	$	120,804

Schedule of the Fair Value of the Company's Financial Assets Measured at Fair Value on a Recurring Basis Based on the Three-tier Value Hierarchy

The following tables set forth the fair value of the Company's financial assets measured at fair value on a recurring basis as of December 31, 2019 and 2018 based on the three-tier value hierarchy described in Note 2, Summary of Significant Accounting Policies:

	December 31, 2019
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents:
Cash	$	308,521	$	—	$	—	$	308,521
Cash equivalents	274,232		—		—		274,232
Total cash and cash equivalents	582,753		—		—		582,753
Short-term investments:
Investment securities	—		404,252		—		404,252
Other non-current assets:
Certificate of deposit	5,076		—		—		5,076
Long-term:
Investment securities	—		155,690		—		155,690
Total	$	587,829	$	559,942	$	—	$	1,147,771

	December 31, 2018
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents:
Cash	$	134,375	$	—	$	—	$	134,375
Cash equivalents	715,086		—		—		715,086
Total cash and cash equivalents	849,461		—		—		849,461
Short-term investments:
Investment securities	—		114,278		—		114,278
Other non-current assets
Certificate of deposit	5,000		—		—		5,000
Long-term:
Investment securities	—		6,526		—		6,526
Total	$	854,461	$	120,804	$	—	$	975,265