Stock Options And Employee Stock Purchase Plan (Allocation Of Share-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allocated Share-based Compensation Expense	$ 8,908	$ 9,720	$ 9,132
Cost Of Revenues [Member]
Allocated Share-based Compensation Expense	345	756	844
Sales And Marketing [Member]
Allocated Share-based Compensation Expense	1,944	1,855	1,543
Research, Development And Engineering [Member]
Allocated Share-based Compensation Expense	721	434	459
General And Administrative [Member]
Allocated Share-based Compensation Expense	$ 5,898	$ 6,675	$ 6,286