Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer			3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Concentration Risk [Line Items]
Number of customers			320
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customers with Largest Net Accounts Receivable Positions [Member]
Concentration Risk [Line Items]
Number of customers	3	3
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer with Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	23.00%	26.00%
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer with Second Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	15.00%	18.00%
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer with Third Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	12.00%	12.00%
Revenue [Member] | Customer Concentration Risk [Member] | Ten Largest Customers [Member]
Concentration Risk [Line Items]
Number of customers			10	10
Concentration risk, percentage of total			62.00%	74.00%