Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 33,951	$ 36,861	$ 35,298
Stock-based compensation expense	33,951	36,861	35,298
Related income tax benefits	(11,656)	(10,927)	(11,096)
Stock-based compensation expense, net of taxes	$ 22,295	$ 25,934	$ 24,202
Basic earnings per share	$ (0.25)	$ (0.28)	$ (0.26)
Diluted earnings per share	$ (0.24)	$ (0.28)	$ (0.25)
Software Licenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 745	$ 1,776	$ 1,349
Maintenance And Service [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	1,868	2,035	2,293
Selling, General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	17,153	17,073	16,847
Research And Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 14,185	$ 15,977	$ 14,809