Balance Sheet Accounts - Schedule of Other Current Assets, net (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred costs recoverable from the U.S. government	$ 43.5	$ 47.1
Income taxes receivable	48.3	43.4
Inventories	10.7	24.0
Prepaid expenses	16.3	13.9
Other	19.7	17.4
Other current assets, net	$ 138.5	$ 145.8

Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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