Accounts Receivable, net (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Transfer of Financial Assets Accounted for as Sales, Amount Derecognized	$ 2,011.7
Accounts Receivable, Net
Trade receivables	458.9	$ 515.2
Other	31.1	32.6
Less: allowance for credit losses	(5.6)	(1.4)
Accounts receivable, net	484.4	546.4
Unbilled Contracts Receivable		528.3
Gain (Loss) on Sale of Accounts Receivable	$ (8.9)	$ (24.7)	$ (16.5)

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Amount of allowance for credit loss on accounts receivable, classified as current.

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Amount of gain (loss) on sale of accounts receivable.

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The sum of amounts currently receivable other than from customers. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

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Amount of derecognized financial assets from transactions which comprise an initial transfer and an agreement entered into in contemplation of the initial transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction, at the date of derecognition.

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Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

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