Financial Instruments and Fair Value , Fair Value Measurements (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | $ 1,075.4 | $ 1,021.5 |
U.S. government and agency securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 479.5 | 461.4 |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 477.7 | 401.8 |
Certificates of deposit and term deposits | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 71.6 | 88.3 |
Corporate debt securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 46.6 | 70 |
Recurring Basis [Member] | Fair Value [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total Assets, Fair Value Disclosure | 1,467 | 1,449.5 |
Recurring Basis [Member] | Fair Value [Member] | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total Assets, Fair Value Disclosure | 714.9 | 731.4 |
Recurring Basis [Member] | Fair Value [Member] | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total Assets, Fair Value Disclosure | 752.1 | 718.1 |
Recurring Basis [Member] | Fair Value [Member] | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total Assets, Fair Value Disclosure | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | U.S. government and agency securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 495.4 | 501.4 |
Recurring Basis [Member] | Fair Value [Member] | U.S. government and agency securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 438.9 | 433.3 |
Recurring Basis [Member] | Fair Value [Member] | U.S. government and agency securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 56.5 | 68.1 |
Recurring Basis [Member] | Fair Value [Member] | U.S. government and agency securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 555.3 | 472.2 |
Recurring Basis [Member] | Fair Value [Member] | Commercial paper | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Commercial paper | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 555.3 | 472.2 |
Recurring Basis [Member] | Fair Value [Member] | Commercial paper | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Certificates of deposit and term deposits | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 92.8 | 104.8 |
Recurring Basis [Member] | Fair Value [Member] | Certificates of deposit and term deposits | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Certificates of deposit and term deposits | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 92.8 | 104.8 |
Recurring Basis [Member] | Fair Value [Member] | Certificates of deposit and term deposits | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Corporate debt securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 47.5 | 73 |
Recurring Basis [Member] | Fair Value [Member] | Corporate debt securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Corporate debt securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 47.5 | 73 |
Recurring Basis [Member] | Fair Value [Member] | Corporate debt securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 254.6 | 277.1 |
Recurring Basis [Member] | Fair Value [Member] | Money market funds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 254.6 | 277.1 |
Recurring Basis [Member] | Fair Value [Member] | Money market funds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Money market funds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Marketable equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 21.4 | 21 |
Recurring Basis [Member] | Fair Value [Member] | Marketable equity securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 21.4 | 21 |
Recurring Basis [Member] | Fair Value [Member] | Marketable equity securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Fair Value [Member] | Marketable equity securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Recurring Basis [Member] | Reported as [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total Assets, Fair Value Disclosure | 1,467 | 1,449.5 |
Recurring Basis [Member] | Reported as [Member] | Cash equivalents | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 370.2 | 407 |
Recurring Basis [Member] | Reported as [Member] | Marketable equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 21.4 | 21 |
Recurring Basis [Member] | Reported as [Member] | Short-term investments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | $ 1,075.4 | $ 1,021.5 |