Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Summary of Cash and Cash Equivalents and Investments' Costs, Gross Unrealized Gains (Losses), and Fair Value by Major Security Type Recorded as Cash and Cash Equivalents or Short-Term or Long-Term Investments

The following tables present our cash and cash equivalents’ and investments’ costs, gross unrealized gains (losses), and fair value by major security type recorded as cash and cash equivalents or short-term or long-term investments as of June 30, 2020 and December 31, 2019 (in thousands):

	As of June 30, 2020
	Cost		Net Unrealized Gains (Losses)		Fair Value		Cash and Cash Equivalents		Short-term Investments		Long-term Investments
Cash	$	42,475	$	—	$	42,475	$	42,475	$	—	$	—
Level 1:
Money market funds	$	57,500	$	—	$	57,500	$	57,500	$	—	$	—
Subtotal	$	57,500	$	—	$	57,500	$	57,500	$	—	$	—
Level 2:
Commercial paper	$	127,310	$	120	$	127,430	$	2,000	$	125,430	$	—
Certificates of deposit	1,000		—		1,000		—		1,000		—
U.S. Treasury and agency bonds	537,097		2,210		539,307		26,200		312,160		200,947
Corporate bonds	205,376		1,350		206,726		—		169,030		37,696
Subtotal	$	870,783	$	3,680	$	874,463	$	28,200	$	607,620	$	238,643
Level 3:	$	—	$	—	$	—	$	—	$	—	$	—
Total	$	970,758	$	3,680	$	974,438	$	128,175	$	607,620	$	238,643
	As of December 31, 2019
	Cost		Net Unrealized Gains (Losses)		Fair Value		Cash and Cash Equivalents		Short-term Investments		Long-term Investments
Cash	$	53,039	$	—	$	53,039	$	53,039	$	—	$	—
Level 1:
Money market funds	$	223,580	$	—	$	223,580	$	223,580	$	—	$	—
Subtotal	$	223,580	$	—	$	223,580	$	223,580	$	—	$	—
Level 2:
Commercial paper	$	217,140	$	(6)	$	217,134	$	98,325	$	118,809	$	—
Certificates of deposit	1,000		—		1,000		—		—		1,000
U.S. Treasury and agency bonds	294,953		199		295,152		35,005		161,767		98,380
Corporate bonds	184,516		444		184,960		—		96,419		88,541
Subtotal	$	697,609	$	637	$	698,246	$	133,330	$	376,995	$	187,921
Level 3:	$	—	$	—	$	—	$	—	$	—	$	—
Total	$	974,228	$	637	$	974,865	$	409,949	$	376,995	$	187,921

Reconciliation of Beginning and Ending Balances of Acquisition-Related Accrued Contingent Consideration

The following table presents a reconciliation of the beginning and ending balances of acquisition-related accrued contingent consideration using significant unobservable inputs (Level 3) for the three and six months ended June 30, 2020 and 2019 (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Beginning balance	$	94	$	393	$	500	$	2,143
Obligations assumed	—		—		—		—
Change in fair value	—		(75)		—		(75)
Settlements	(94)		—		(500)		(1,750)
Ending balance	$	—	$	318	$	—	$	318