Balance Sheet Accounts - Schedule of Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Billed receivables under long-term contracts	$ 152.5	$ 122.9
Reserve on billed trade receivables	(1.0)	(10.6)
Other trade receivables	0.2	0.2
Accounts receivable, net	$ 151.7	$ 112.5