v3.20.4

Marketable Securities - Schedule of Marketable Securities and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Total marketable securities [Member]
Cash And Cash Equivalents [Line Items]
Amortized Cost	$ 257,752	$ 49,608
Unrealized Gains	12
Unrealized Losses	(9)	(6)
Fair Value	257,755	49,602
U S Government Agencies Debt Securities [Member]
Cash And Cash Equivalents [Line Items]
Amortized Cost	105,358	10,047
Unrealized Gains	6
Unrealized Losses	(5)	(1)
Fair Value	105,359	10,046
Corporate Debt Securities [Member]
Cash And Cash Equivalents [Line Items]
Amortized Cost	52,529	12,753
Unrealized Gains	6
Unrealized Losses	(4)	(5)
Fair Value	52,531	12,748
Commercial Paper [Member]
Cash And Cash Equivalents [Line Items]
Amortized Cost	99,865	26,808
Fair Value	$ 99,865	$ 26,808

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

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-SubTopic 10
-Section 50
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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

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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)
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CONSTELLATION PHARMACEUTICALS INC 10-K