Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Commitments And Contingencies [Line Items]
Rent expense for operating leases	$ 253.7	$ 239.8	$ 223.4
Contingent rent expense	25.0	24.4	23.3
Long term purchase commitment milestone	5.7	4.1	$ 18.7
Estimated obligation for long term purchase commitment milestones	4.1
Maximum obligation for long term purchase commitment milestones	$ 5.8	$ 10.2
Non-cancelable Operating Leases [Member]
Schedule Of Commitments And Contingencies [Line Items]
Lease expiration period	Dec. 01, 2152
Non-cancelable Capital Leases [Member]
Schedule Of Commitments And Contingencies [Line Items]
Lease expiration period	Aug. 01, 2020
Minimum [Member]
Schedule Of Commitments And Contingencies [Line Items]
Business acquisitions performance target period	1 year
Maximum [Member]
Schedule Of Commitments And Contingencies [Line Items]
Business acquisitions performance target period	3 years