Financial Instruments - Schedule Of Available-For-Sale Investments With Unrealized Losses (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	$ 4,856.7	$ 715.6
Unrealized losses less than 12 months	(31.2)	(0.2)
Unrealized losses 12 months or greater, fair value	0.0	0.0
Unrealized losses 12 months or greater	0.0	0.0
Total Fair Value	4,856.7	715.6
Total Unrealized Losses	(31.2)	(0.2)
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	4.0
Unrealized losses less than 12 months	0.0
Unrealized losses 12 months or greater, fair value	0.0
Unrealized losses 12 months or greater	0.0
Total Fair Value	4.0
Total Unrealized Losses	0.0
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	1,687.9	352.7
Unrealized losses less than 12 months	(11.9)	(0.2)
Unrealized losses 12 months or greater, fair value	0.0	0.0
Unrealized losses 12 months or greater	0.0	0.0
Total Fair Value	1,687.9	352.7
Total Unrealized Losses	(11.9)	(0.2)
U.S. treasuries
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	2,596.3	278.1
Unrealized losses less than 12 months	(15.4)	0.0
Unrealized losses 12 months or greater, fair value	0.0	0.0
Unrealized losses 12 months or greater	0.0	0.0
Total Fair Value	2,596.3	278.1
Total Unrealized Losses	(15.4)	0.0
U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	412.5	63.5
Unrealized losses less than 12 months	(2.9)	0.0
Unrealized losses 12 months or greater, fair value	0.0	0.0
Unrealized losses 12 months or greater	0.0	0.0
Total Fair Value	412.5	63.5
Total Unrealized Losses	(2.9)	0.0
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months, fair value	156.0	21.3
Unrealized losses less than 12 months	(1.0)	0.0
Unrealized losses 12 months or greater, fair value	0.0	0.0
Unrealized losses 12 months or greater	0.0	0.0
Total Fair Value	156.0	21.3
Total Unrealized Losses	$ (1.0)	$ 0.0

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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