Summary Of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) customer	Dec. 31, 2016 USD ($) customer	Dec. 31, 2015
Concentration Risk [Line Items]
Concentration of risk	100.00%	100.00%	100.00%
Allowance for doubtful accounts | $	$ 1,181,000	$ 0
Aggregate gross trade receivables | Customer Concentration Risk
Concentration Risk [Line Items]
Number of customers, concentration of risk disclosure | customer	3	2
Customer One | Aggregate gross trade receivables | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk	17.00%	14.00%
Customer Two | Aggregate gross trade receivables | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk	11.00%	13.00%
Customer Three | Aggregate gross trade receivables | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk	10.00%
Micron Technology, Inc. | Total revenues | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk	11.00%	17.00%	15.00%
Amkor Technologies, Inc. | Total revenues | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk	10.00%	15.00%	14.00%
Samsung Electronics, Co. Ltd. | Total revenues | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk		25.00%	19.00%
SK hynix Inc. | Total revenues | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration of risk		12.00%	13.00%