Revenue Recognition (Adoption of ASC 606) - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Accounts receivable	$ 95.0	$ 95.0	$ 136.5
Performance obligation satisfied in previous period	4.7	11.8
Performance obligation	$ 25.4	$ 25.4
Transferred over Time \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation percentage	87.00%	87.00%
Expected timing of satisfaction period	12 months	12 months
Transferred over Time \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation percentage	13.00%	13.00%
Expected timing of satisfaction period	24 months	24 months

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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