Selected Balance Sheet Data, Accounts Receivable (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Accounts Receivable, Net
Accounts receivable	$ 58.2	$ 80.7
Less allowance for bad debts	(4.6)	(5.6)
Accounts receivable, net	$ 53.6	$ 75.1

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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant