Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 33,347	$ 33,951	$ 36,861
Stock-based compensation expense	33,347	33,951	36,861
Related income tax benefits	(10,538)	(11,656)	(10,927)
Stock-based compensation expense, net of taxes	$ 22,809	$ 22,295	$ 25,934
Basic earnings per share	$ (0.26)	$ (0.25)	$ (0.28)
Diluted earnings per share	$ (0.26)	$ (0.24)	$ (0.28)
Software Licenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 701	$ 745	$ 1,776
Maintenance And Service [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	1,578	1,868	2,035
Selling, General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	15,990	17,153	17,073
Research And Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 15,078	$ 14,185	$ 15,977