Summary of Quarterly Operating Results and Comprehensive Income (Narrative) (Details) $ in Millions	3 Months Ended
Dec. 31, 2017 USD ($)
Periods from Q3 2016 to Q3 2017 [Member]
Quantifying Misstatement in Current Year Financial Statements [Line Items]
Prior Period Reclassification Adjustment	$ 2.8

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.

No definition available.

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