Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Commitments And Contingencies [Line Items]
Rent expense for operating leases	$ 266.4	$ 253.7	$ 239.8
Contingent rent expense	$ 26.6	$ 25.0	$ 24.4
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	Sep. 01, 2021
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