Revenue Recognition - Narrative (Details) - Accounting Standards Update 2014-09 - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Jan. 01, 2018
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized from deferred revenue	$ 21.0
Contract asset reclassified to receivables	$ 4.0
Retained Earnings
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Net increase to opening retained earnings		$ 12.9

Amount of decrease in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time from transfer to receivable due to right to consideration becoming unconditional.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130551-203045

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130549-203045

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84173487&loc=SL51747714-108306

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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