Property And Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Capitalized software development costs	$ 14.8	$ 15.7	$ 16.5
Unamortized software development costs	29.9
Total depreciation expense and amortization of capitalized software development costs	20.6	18.5	13.2
Software And Capitalized Software Development Costs
Property, Plant and Equipment [Line Items]
Amortization expense	$ 12.1	$ 11.8	$ 8.8