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Cash, Cash Equivalents, Marketable Securities, and Restricted Cash - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash and cash equivalents	$ 184,833,000	$ 163,240,000	$ 123,231,000
Available-for-sale debt securities	232,596,000	320,029,000
Realized gain (loss) on debt securities	0	0
Fair value of available-for-sale debt securities in unrealized loss positions	$ 114,500,000	$ 124,900,000

X

- Definition

Amount of 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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-Publisher FASB
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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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