Income Taxes (Schedule Of A Reconciliation Of The Statutory Rate To The Effective Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
INCOME TAXES [Abstract]
Federal statutory rate (as a percent)	34.00%	34.00%	34.00%
State income taxes, net of federal benefit (as a percent)	2.30%	0.10%	(0.20%)
U.S. Subpart F income (as a percent)	1.60%	3.20%	(1.00%)
Earnings and dividends of foreign affiliate (as a percent)	0.00%	32.20%	(28.90%)
Stock based compensation (as a percent)	(19.80%)	0.50%	(1.40%)
Research and experimentation credit (as a percent)	(13.90%)	(2.20%)	4.60%
Foreign rate difference (as a percent)	13.60%	(7.10%)	17.80%
Reserve for income taxes (as a percent)	(93.80%)	0.00%	0.00%
Valuation allowance (as a percent)	26.10%	(141.90%)	(26.10%)
Other, net (as a percent)	5.40%	0.30%	(0.10%)
Effective tax rate (as a percent)	(44.50%)	(80.90%)	(1.30%)