Fair Value Measurement - (Detail) - USD ($) $ in Thousands |
Mar. 31, 2021 |
Sep. 30, 2020 |
---|---|---|
Assets | ||
Assets, Totals | $ 555,658 | $ 290,002 |
Commercial Paper [Member] | ||
Assets | ||
Assets, Totals | 74,958 | 94,840 |
US Government Treasury Bills [Member] | ||
Assets | ||
Assets, Totals | 81,371 | 101,495 |
Cash [Member] | ||
Assets | ||
Assets, Totals | 33,515 | 20,254 |
Money Market Funds [Member] | ||
Assets | ||
Assets, Totals | 365,814 | 73,413 |
Fair Value, Inputs, Level 1 [Member] | ||
Assets | ||
Assets, Totals | 480,700 | 195,162 |
Fair Value, Inputs, Level 1 [Member] | US Government Treasury Bills [Member] | ||
Assets | ||
Assets, Totals | 81,371 | 101,495 |
Fair Value, Inputs, Level 1 [Member] | Cash [Member] | ||
Assets | ||
Assets, Totals | 33,515 | 20,254 |
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member] | ||
Assets | ||
Assets, Totals | 365,814 | 73,413 |
Fair Value, Inputs, Level 2 [Member] | ||
Assets | ||
Assets, Totals | 74,958 | 94,840 |
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member] | ||
Assets | ||
Assets, Totals | $ 74,958 | $ 94,840 |