Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer			3 Months Ended		9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Concentration Risk [Line Items]
Number of customers					435
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	2	2
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	36.00%	46.00%
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	27.00%	15.00%
Revenue [Member] | Customer Concentration Risk [Member] | Ten Largest Customers [Member]
Concentration Risk [Line Items]
Number of customers			10	10	10	10
Concentration risk, percentage of total			76.00%	83.00%	73.00%	80.00%