v3.26.1
Fair Value Measurements - Fair Value of Financial Assets by Level (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Financial Assets:    
Cash Equivalents: $ 767.1 $ 1,336.1
Marketable Securities: 11,053.1  
Marketable Securities 11,053.1 8,779.1
Money market funds - restricted cash 1.4 1.4
Total Financial Assets 11,821.6 10,116.6
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 11,147.8 8,914.4
Unrealized Gains 2.3 27.5
Unrealized Losses (40.8) (1.5)
Fair Value 11,109.3 8,940.4
Commercial paper    
Financial Assets:    
Marketable Securities: 538.5 83.0
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 580.3 112.8
Unrealized Gains 0.0 0.0
Unrealized Losses 0.0 0.0
Fair Value 580.3 112.8
U.S. government notes    
Financial Assets:    
Marketable Securities: 2,872.8 2,854.3
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 2,881.6 2,970.4
Unrealized Gains 0.6 8.8
Unrealized Losses (9.4) 0.0
Fair Value 2,872.8 2,979.2
Corporate bonds    
Financial Assets:    
Marketable Securities: 6,274.3 4,329.7
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 6,310.1 4,321.2
Unrealized Gains 1.6 16.0
Unrealized Losses (23.0) (0.9)
Fair Value 6,288.7 4,336.3
Municipal bonds    
Financial Assets:    
Marketable Securities: 17.5 14.5
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 17.6 14.5
Unrealized Gains 0.0 0.0
Unrealized Losses (0.1) 0.0
Fair Value 17.5 14.5
Agency securities    
Financial Assets:    
Marketable Securities: 1,350.0 1,497.6
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]    
Amortized Cost 1,358.2 1,495.5
Unrealized Gains 0.1 2.7
Unrealized Losses (8.3) (0.6)
Fair Value 1,350.0 1,497.6
Money market funds    
Financial Assets:    
Cash Equivalents: 710.9 1,174.8
Commercial paper    
Financial Assets:    
Cash Equivalents: 41.8 29.8
Corporate bonds    
Financial Assets:    
Cash Equivalents: 14.4 6.6
U.S. government notes    
Financial Assets:    
Cash Equivalents: 0.0 124.9
Level I    
Financial Assets:    
Cash Equivalents: 710.9 1,299.7
Marketable Securities 2,872.8 2,854.3
Money market funds - restricted cash 1.4 1.4
Total Financial Assets 3,585.1 4,155.4
Level I | Commercial paper    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level I | U.S. government notes    
Financial Assets:    
Marketable Securities: 2,872.8 2,854.3
Level I | Corporate bonds    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level I | Municipal bonds    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level I | Agency securities    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level I | Money market funds    
Financial Assets:    
Cash Equivalents: 710.9 1,174.8
Level I | Commercial paper    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level I | Corporate bonds    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level I | U.S. government notes    
Financial Assets:    
Cash Equivalents: 0.0 124.9
Level II    
Financial Assets:    
Cash Equivalents: 56.2 36.4
Marketable Securities 8,180.3 5,924.8
Money market funds - restricted cash 0.0 0.0
Total Financial Assets 8,236.5 5,961.2
Level II | Commercial paper    
Financial Assets:    
Marketable Securities: 538.5 83.0
Level II | U.S. government notes    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level II | Corporate bonds    
Financial Assets:    
Marketable Securities: 6,274.3 4,329.7
Level II | Municipal bonds    
Financial Assets:    
Marketable Securities: 17.5 14.5
Level II | Agency securities    
Financial Assets:    
Marketable Securities: 1,350.0 1,497.6
Level II | Money market funds    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level II | Commercial paper    
Financial Assets:    
Cash Equivalents: 41.8 29.8
Level II | Corporate bonds    
Financial Assets:    
Cash Equivalents: 14.4 6.6
Level II | U.S. government notes    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level III    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Marketable Securities 0.0 0.0
Money market funds - restricted cash 0.0 0.0
Total Financial Assets 0.0 0.0
Level III | Commercial paper    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level III | U.S. government notes    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level III | Corporate bonds    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level III | Municipal bonds    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level III | Agency securities    
Financial Assets:    
Marketable Securities: 0.0 0.0
Level III | Money market funds    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level III | Commercial paper    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level III | Corporate bonds    
Financial Assets:    
Cash Equivalents: 0.0 0.0
Level III | U.S. government notes    
Financial Assets:    
Cash Equivalents: $ 0.0 $ 0.0