Stock Options And Employee Stock Purchase Plan (Allocation Of Share-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Allocated Share-based Compensation Expense	$ 2,425	$ 2,403	$ 7,108	$ 6,851
Cost Of Revenues [Member]
Allocated Share-based Compensation Expense	162	199	581	633
Sales And Marketing [Member]
Allocated Share-based Compensation Expense	465	390	1,315	1,117
Research, Development And Engineering [Member]
Allocated Share-based Compensation Expense	103	111	311	344
General And Administrative [Member]
Allocated Share-based Compensation Expense	$ 1,695	$ 1,703	$ 4,901	$ 4,757