Basis of Presentation Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Organization Consolidation And Presentation [Line Items]
Deferred tax benefit, 2017 Tax Act	$ 3.6

[Line Items] for Disclosures of organization, consolidation and basis of presentation of financial statements.

No definition available.

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