Stock Options And Employee Stock Purchase Plan (Allocation Of Share-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allocated Share-based Compensation Expense	$ 3,004	$ 2,384
Cost Of Revenues [Member]
Allocated Share-based Compensation Expense	83	154
Sales And Marketing [Member]
Allocated Share-based Compensation Expense	584	491
Research, Development And Engineering [Member]
Allocated Share-based Compensation Expense	194	140
General And Administrative [Member]
Allocated Share-based Compensation Expense	$ 2,143	$ 1,599