Stock Options And Employee Stock Purchase Plan (Allocation Of Share-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Allocated Share-based Compensation Expense	$ 2,335	$ 2,155	$ 4,683	$ 4,448
Cost Of Revenues [Member]
Allocated Share-based Compensation Expense	205	192	419	434
Sales And Marketing [Member]
Allocated Share-based Compensation Expense	432	352	850	727
Research, Development And Engineering [Member]
Allocated Share-based Compensation Expense	102	117	208	233
General And Administrative [Member]
Allocated Share-based Compensation Expense	$ 1,596	$ 1,494	$ 3,206	$ 3,054