Property And Equipment (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Capitalized software development costs	$ 5.4	$ 5.8	$ 17.0	$ 15.4
Computers and equipment
Property, Plant and Equipment [Line Items]
Capital leased assets, gross	1.4		1.4		$ 1.7
Capital leased assets, accumulated depreciation	0.9		0.9		$ 1.1
Software and software development costs
Property, Plant and Equipment [Line Items]
Amortization expense related to capitalized software development	4.1	3.0	11.6	8.7
Unamortized software development costs	39.9		39.9
Depreciation expense including amortization of capitalized software development costs	$ 7.9	$ 6.0	$ 22.0	$ 16.8

Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

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The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=84164758&loc=d3e45014-112735

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Additions made to capitalized computer software costs during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Amount of expense for amortization of capitalized computer software costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
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The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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No definition available.

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