Available-for-Sale Securities and Fair Value Measurements - Schedule of Available-for-Sale Securities (Details) - Estimate of fair value measurement - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 331,435	$ 302,247
Gross Unrealized Gains	713	270
Gross Unrealized Losses	(393)	(11)
Estimated Fair Value	331,755	302,506
Corporate bonds \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	115,877	109,780
Gross Unrealized Gains	22	136
Gross Unrealized Losses	(300)	(6)
Estimated Fair Value	115,599	109,910
Commercial paper \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	34,191	41,237
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	34,191	41,237
Asset-backed securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	39,803	57,195
Gross Unrealized Gains	9	63
Gross Unrealized Losses	(93)	(5)
Estimated Fair Value	39,719	57,253
Repurchase agreements \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	18,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	0	18,000
U.S. treasury securities \| Level 1
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	74,337	75,574
Gross Unrealized Gains	682	71
Gross Unrealized Losses	0	0
Estimated Fair Value	75,019	75,645
Money market funds \| Level 1
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	67,227	461
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 67,227	$ 461

Available for sale securities including cash equivalents.

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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