Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer			3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Concentration Risk [Line Items]
Number of customers			295
Accounts Receivable, Net, Less Deferred Revenue [Member] | Credit Concentration Risk [Member] | Customers with Largest Net Accounts Receivable Positions [Member]
Concentration Risk [Line Items]
Number of customers	2	3
Accounts Receivable, Net, Less Deferred Revenue [Member] | Credit Concentration Risk [Member] | Customer with Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	16.00%	17.00%
Accounts Receivable, Net, Less Deferred Revenue [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%	13.00%
Accounts Receivable, Net, Less Deferred Revenue [Member] | Credit Concentration Risk [Member] | Customer with Third Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total		11.00%
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%	62.00%