Other Financial Statement Details - Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2019	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 810.8	$ 882.6
Less allowance for doubtful accounts	3.3	2.0
Total accounts receivable, net	807.5	880.6
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	799.3	875.8
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivable amounts	$ 11.5	$ 6.8