Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer			3 Months Ended		6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Concentration Risk [Line Items]
Number of customers					375
Accounts Receivable, Net, Less Billings in Excess of Costs and Earnings [Member] | Credit Concentration Risk [Member] | Customer with Highest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Number of customers	1	1
Concentration risk, percentage of total	48.00%	24.00%
Accounts Receivable, Net, Less Billings in Excess of Costs and Earnings [Member] | Credit Concentration Risk [Member] | Customer with Second Highest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	11.00%	17.00%
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			84.00%	76.00%	79.00%	74.00%