Fair Value Measurements - Fair Value on Recurring Basis (Details) - USD ($) $ in Millions | Sep. 30, 2022 | Dec. 31, 2021 |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | $ 372 | $ 533 |
Short-term investments | 1,081.4 | 1,185.1 |
U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 314.9 | 237.5 |
Asset backed securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 112 | 139.6 |
Municipal securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 62.3 | 69.8 |
Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 41.4 | 61.7 |
Certificates of deposit | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 26 | 32.1 |
U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 13.7 | 14.4 |
Foreign government obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 6 | 18.3 |
Supranational securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 3.1 | 7.9 |
Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 279.2 | 390.3 |
U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2.5 | |
Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2 | |
Fair Value, Measurements, Recurring | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 285.3 | 390.3 |
Short-term investments | 1,081.4 | 1,185.1 |
Assets, fair value disclosure | 1,366.7 | 1,575.4 |
Fair Value, Measurements, Recurring | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 502 | 603.8 |
Fair Value, Measurements, Recurring | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 314.9 | 237.5 |
Fair Value, Measurements, Recurring | Asset backed securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 112 | 139.6 |
Fair Value, Measurements, Recurring | Municipal securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 62.3 | 69.8 |
Fair Value, Measurements, Recurring | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 41.4 | 61.7 |
Fair Value, Measurements, Recurring | Certificates of deposit | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 26 | 32.1 |
Fair Value, Measurements, Recurring | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 13.7 | 14.4 |
Fair Value, Measurements, Recurring | Foreign government obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 6 | 18.3 |
Fair Value, Measurements, Recurring | Supranational securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 3.1 | 7.9 |
Fair Value, Measurements, Recurring | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 279.2 | 390.3 |
Fair Value, Measurements, Recurring | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2.5 | |
Fair Value, Measurements, Recurring | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2 | |
Fair Value, Measurements, Recurring | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 1.6 | |
Fair Value, Measurements, Recurring | Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 279.2 | 390.3 |
Short-term investments | 0 | 0 |
Assets, fair value disclosure | 279.2 | 390.3 |
Fair Value, Measurements, Recurring | Level 1 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Asset backed securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Municipal securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Certificates of deposit | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Foreign government obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Supranational securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 1 | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 279.2 | 390.3 |
Fair Value, Measurements, Recurring | Level 1 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | |
Fair Value, Measurements, Recurring | Level 1 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | |
Fair Value, Measurements, Recurring | Level 1 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | |
Fair Value, Measurements, Recurring | Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 6.1 | 0 |
Short-term investments | 1,081.4 | 1,185.1 |
Assets, fair value disclosure | 1,087.5 | 1,185.1 |
Fair Value, Measurements, Recurring | Level 2 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 502 | 603.8 |
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 314.9 | 237.5 |
Fair Value, Measurements, Recurring | Level 2 | Asset backed securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 112 | 139.6 |
Fair Value, Measurements, Recurring | Level 2 | Municipal securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 62.3 | 69.8 |
Fair Value, Measurements, Recurring | Level 2 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 41.4 | 61.7 |
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 26 | 32.1 |
Fair Value, Measurements, Recurring | Level 2 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 13.7 | 14.4 |
Fair Value, Measurements, Recurring | Level 2 | Foreign government obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 6 | 18.3 |
Fair Value, Measurements, Recurring | Level 2 | Supranational securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 3.1 | 7.9 |
Fair Value, Measurements, Recurring | Level 2 | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | 0 |
Fair Value, Measurements, Recurring | Level 2 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2.5 | |
Fair Value, Measurements, Recurring | Level 2 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 2 | |
Fair Value, Measurements, Recurring | Level 2 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 1.6 | |
Fair Value, Measurements, Recurring | Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Assets, fair value disclosure | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Asset backed securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Municipal securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Certificates of deposit | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Foreign government obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Supranational securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Short-term investments | 0 | 0 |
Fair Value, Measurements, Recurring | Level 3 | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | $ 0 |
Fair Value, Measurements, Recurring | Level 3 | U.S. agency obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | |
Fair Value, Measurements, Recurring | Level 3 | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | 0 | |
Fair Value, Measurements, Recurring | Level 3 | Corporate notes and obligations | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Cash equivalents | $ 0 | |