Operations And Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	$ 73,117	$ 81,789
Net sale of short-term investments	9,000
Allowances for sales returns	1,800	1,900
Allowances for doubtful accounts	1,900	2,500
Cumulative net adjustment for excess and obsolete inventories	12,639	10,054	$ 9,598	$ 5,459
Goodwill impairment	$ 0	0
Number of operating segments | segment	1
Number of reporting units | segment	1
Cash and cash equivalents	$ 285,283	$ 251,129	$ 274,030	$ 230,263
Investment policy for marketable securities	Our investment policy for marketable securities requires that all securities mature in five years or less, with a weighted average maturity of no longer than 24 months with at least 10% maturing in 90 days or less.
Maximum maturity period for marketable securities	5 years
Minimum percentage maturing in 90 days or less	10.00%
Maturity period	90 days
Percentage of sales to any individual customer to total revenue	3.00%	3.00%	5.00%
Largest trade account receivable from any individual customer	$ 4,000
Licensing and sales arrangement payment term, minimum (in days)	30 days
Concentrated orders	$ 1,000
Licensing and sales arrangement payment term, maximum (in days)	120 days
Maximum period of return after delivering of product (in days)	30 days
Warranty on products, minimum (in days)	90 days
Warranty on Products, maximum (in years)	3 years
Limited warranty on most hardware products (in number of years)	1 year
Advertising expense	$ 12,000	$ 12,000	$ 14,000
Anti-dilutive securities excluded from the computation of diluted EPS | shares	10,900	292,400	19,400
Comprehensive income	$ 86,203	$ 68,836	$ 112,119
Operating Account [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 217,000
Percentage of cash and cash equivalents	76.00%
Money Market Accounts [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 69,000
Percentage of cash and cash equivalents	24.00%
Domestic Financial Institutions [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 46,000
Percentage of cash and cash equivalents	16.00%
Non U.S. Financial Institutions [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 239,000
Percentage of cash and cash equivalents	84.00%
Corporate Bonds Denominated In Euros [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	$ 4,400
Corporate Bonds [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	$ 71,000
Percentage of short-term investments	98.00%
Time Deposits [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	$ 1,800
Percentage of short-term investments	2.00%
Wells Fargo Operating Account [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 11,000
Percentage of cash and cash equivalents	4.00%
Minimum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	20 years
Minimum [Member] | Furniture And Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Minimum [Member] | Patents [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	10 years
Maximum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	40 years
Maximum [Member] | Furniture And Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	7 years
Maximum [Member] | Patents [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	17 years