Marketable Securities (Details) - USD ($) |
Mar. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2017 |
|---|---|---|---|
| Debt Securities, Available-for-sale [Line Items] | |||
| Amortized Cost | $ 124,670,000 | $ 91,407,000 | |
| Gross Unrealized Gains | 14,000 | 3,000 | |
| Gross Unrealized Losses | (3,000) | (10,000) | |
| Fair Value | 124,681,000 | 91,400,000 | |
| Allowance for credit loss related to available-for-sale debt securities | 0 | 0 | |
| U.S. Treasury securities | |||
| Debt Securities, Available-for-sale [Line Items] | |||
| Amortized Cost | 79,775,000 | $ 60,630,000 | |
| Gross Unrealized Gains | 12,000 | 1,000 | |
| Gross Unrealized Losses | 0 | (7,000) | |
| Fair Value | 79,787,000 | $ 60,624,000 | |
| Government-sponsored enterprises | |||
| Debt Securities, Available-for-sale [Line Items] | |||
| Amortized Cost | 4,570,000 | ||
| Gross Unrealized Gains | 0 | ||
| Gross Unrealized Losses | 0 | ||
| Fair Value | 4,570,000 | ||
| Corporate debt securities | |||
| Debt Securities, Available-for-sale [Line Items] | |||
| Amortized Cost | 40,325,000 | 30,777,000 | |
| Gross Unrealized Gains | 2,000 | 2,000 | |
| Gross Unrealized Losses | (3,000) | (3,000) | |
| Fair Value | $ 40,324,000 | $ 30,776,000 |