Summary of Significant Accounting Policies (Intangible Assets) (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	1 year
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	20 years
Weighted Average
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	14 years
Internally Used Software | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Internally Used Software | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years