Summary of Significant Accounting Policies (Concentration of Credit Risk Narrative) (Details) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Sales Revenue | First Largest Customer [Member]
Concentration Risk [Line Items]
Concentration risk percentage	16.00%	19.00%	19.00%
Sales Revenue | Second Largest Customer [Member]
Concentration Risk [Line Items]
Concentration risk percentage	14.00%	10.00%
Accounts Receivable [Member] | First Largest Customer [Member]
Concentration Risk [Line Items]
Concentration risk percentage	9.00%	4.00%	11.00%
Accounts Receivable [Member] | Second Largest Customer [Member]
Concentration Risk [Line Items]
Concentration risk percentage	3.00%	1.00%