Operations And Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary Of Significant Accounting Policies [Line Items]
Maximum contractual maturity period of short-term investments available for sale (in months)	40 months
Maximum remaining maturity period of sovereign debt	5 months
Fair value of short-term investments in debt securities	$ 197,163,000	$ 163,149,000
Net sale of short-term investments	34,000,000
German government sovereign debt, in USD	7,300,000
Allowances for sales returns	1,800,000	1,600,000
Allowances for doubtful accounts	3,000,000	2,800,000
Cumulative net adjustment for excess and obsolete inventories	9,598,000	5,459,000	3,844,000	4,205,000
Cash and cash equivalents	274,030,000	230,263,000	161,996,000	142,608,000
Investment policy for marketable securities	Our investment policy for marketable securities requires that all securities mature in three years or less, with a weighted average maturity of no longer than 18 months with at least 10% maturing in 90 days or less.
Maximum maturity period for marketable securities	3 years
Maximum weighted-average maturity period	18 months
Minimum percentage maturing in 90 days or less	10.00%
Maturity period	90 days
Percentage of sales to any individual customer to total revenue	5.00%	3.00%	7.00%
Largest trade account receivable from any individual customer	3,700,000
Licensing and sales arrangement payment term, minimum (in days)	30 days
Concentrated orders	1,000,000
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
Advertising expense	14,000,000	14,000,000	14,000,000
Anti-dilutive securities excluded from the computation of diluted EPS	19,400	43,600	986,500
Decrease in deferred tax assets due to new accountin pronouncements	944,000
Comprehensive income	112,119,000	82,219,000	94,481,000
Operating Account [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	150,000,000
Percentage of cash and cash equivalents	55.00%
Money Market Accounts [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	124,000,000
Percentage of cash and cash equivalents	45.00%
Domestic Financial Institutions [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	91,000,000
Percentage of cash and cash equivalents	33.00%
Non U.S. Financial Institutions [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	183,000,000
Percentage of cash and cash equivalents	67.00%
Foreign Government Bonds [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	7,000,000
Percentage of short-term investments	4.00%
U.S. Treasuries And Agencies [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	74,000,000
Percentage of short-term investments	37.00%
Corporate Bonds Denominated In Euros [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	23,000,000
Corporate Bonds [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	113,000,000
Percentage of short-term investments	57.00%
Time Deposits [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of short-term investments in debt securities	3,000,000
Percentage of short-term investments	2.00%
Wells Fargo Operating Account [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 23,000,000
Percentage of cash and cash equivalents	9.00%
Capitalized Software Development Costs [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	3 years
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