Summary of Significant Accounting Policies (Foreign Currency Exchange) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Net unrealized foreign currency translation losses	$ (3.9)	$ (1.3)

Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant