Investments (Debt Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	$ 2,414.8	$ 2,858.9
Accumulated unrealized loss	(4.8)	(4.3)
Fair value	2,410.0	2,854.6
Contractual maturity:
Due in one year or less	2,187.9
Due in one to five years	221.0
Due in five to ten years	1.1
Fair value	2,410.0	2,854.6
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	831.4	881.1
Accumulated unrealized loss	0.1	2.1
Fair value	831.5	883.2
Contractual maturity:
Fair value	831.5	883.2
Government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	596.1	697.0
Accumulated unrealized loss	(1.6)	(1.4)
Fair value	594.5	695.6
Contractual maturity:
Fair value	594.5	695.6
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	481.6	520.5
Accumulated unrealized loss	(0.3)	(0.6)
Fair value	481.3	519.9
Contractual maturity:
Fair value	481.3	519.9
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	316.0	405.3
Accumulated unrealized loss	(3.0)	(4.8)
Fair value	313.0	400.5
Contractual maturity:
Fair value	313.0	400.5
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost basis	189.7	355.0
Accumulated unrealized loss	0.0	0.4
Fair value	189.7	355.4
Contractual maturity:
Fair value	$ 189.7	$ 355.4
Weighted Average
Contractual maturity:
Weighted average life	4 months 24 days

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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