Financial Assets and Liabilities - Short-term investments (Details) - Cash equivalents - USD ($) $ in Thousands |
Jul. 31, 2020 |
Oct. 31, 2019 |
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|---|---|---|---|---|---|---|---|---|
| Cash Equivalents [Line Items] | ||||||||
| Cost | $ 280,417 | $ 166,024 | ||||||
| Gross unrealized gains | 0 | 0 | ||||||
| Gross unrealized losses less than 12 months | 0 | 0 | ||||||
| Gross unrealized losses 12 months or longer | 0 | 0 | ||||||
| Estimated fair value | 280,417 | [1] | 166,024 | [2] | ||||
| Money market funds | ||||||||
| Cash Equivalents [Line Items] | ||||||||
| Cost | 280,417 | 166,024 | ||||||
| Gross unrealized gains | 0 | 0 | ||||||
| Gross unrealized losses less than 12 months | 0 | 0 | ||||||
| Gross unrealized losses 12 months or longer | 0 | 0 | ||||||
| Estimated fair value | $ 280,417 | [1] | $ 166,024 | [2] | ||||
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