Property And Equipment, Net (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense of property and equipment	$ 48.8	$ 42.8	$ 39.8
New Westbrook Administrative Facility [Member]
Property, Plant and Equipment [Line Items]
Current year additions		19.9	13.9
Software Developed For Internal Use [Member]
Property, Plant and Equipment [Line Items]
Current year additions	$ 11.9	$ 10.9	$ 12.4