Stock-Based Compensation (Classification Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 6,083		$ 7,413
Tax benefit associated with stock-based compensation expense	2,385	[1]	2,869	[1]
Reduction of net income	3,698		4,544
Recognized tax benefit related to share-based compensation expense	39.20%		38.70%
Cost Of Services [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	232		316
Sales And Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	1,728		2,109
Research And Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	1,497		2,152
General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 2,628		$ 2,836

[1] The recognized tax benefit related to stock-based compensation expense was estimated to be 39.2% and 38.7% for the quarter ended March 31, 2012 and 2011, respectively. This approximates the blended Federal and State statutory tax rate after the benefit for state taxes.