Amount of the cost of borrowed funds accounted for as interest expense.

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Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Debt - Short-Term Borrowings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Line of Credit Facility [Line Items]
Short-term borrowings	$ 110.0		$ 110.0		$ 235.0
Interest expense, net	1.4	$ 1.8	5.1	$ 4.9
Revolving Credit Facility
Line of Credit Facility [Line Items]
Short-term borrowings	110.0		110.0		$ 235.0
Minimum
Line of Credit Facility [Line Items]
Short-term borrowings	80.0	140.0	80.0	140.0
Maximum
Line of Credit Facility [Line Items]
Short-term borrowings	$ 257.0	$ 249.0	$ 257.0	$ 249.0