Cash Equivalents and Investments - Restricted Cash and Investments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,068.1	$ 880.1
Total cash, cash equivalents, and restricted cash	1,084.3	897.7	$ 942.7	$ 1,383.0
Prepaid expenses and other current assets
Cash and Cash Equivalents [Line Items]
Restricted cash included in Prepaid expenses and other current assets and Other long-term assets	13.8	15.2
Other long-term assets
Cash and Cash Equivalents [Line Items]
Restricted cash included in Prepaid expenses and other current assets and Other long-term assets	$ 2.4	$ 2.4