Principles Of Consolidation (Claims and Insurance) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Workers' Compensation [Member]
LIability For Unpaid Claims And Claim Adjustment Expense, Adjustment Of Opening Balance [Roll Forward]
Undiscounted amount	$ 449.6	$ 446.6
Claim payments, net of recoveries	(140.9)	(124.5)
Estimated settlement cost	100.4	106.9
Change in estimated settlement cost for older claim years	(19.0)	20.6
Undiscounted amount	390.1	449.6
Discounted settlement cost estimate	351.2
Property Damage and Liability Claims [Member]
LIability For Unpaid Claims And Claim Adjustment Expense, Adjustment Of Opening Balance [Roll Forward]
Undiscounted amount	79.9	102.1
Claim payments, net of recoveries	(43.7)	(66.5)
Estimated settlement cost	27.4	32.4
Change in estimated settlement cost for older claim years	1.5	11.9
Undiscounted amount	65.1	79.9
Discounted settlement cost estimate	65.1
Total [Member]
LIability For Unpaid Claims And Claim Adjustment Expense, Adjustment Of Opening Balance [Roll Forward]
Undiscounted amount	529.5	548.7
Claim payments, net of recoveries	(184.6)	(191.0)
Estimated settlement cost	127.8	139.3
Change in estimated settlement cost for older claim years	(17.5)	32.5
Undiscounted amount	455.2	529.5
Discounted settlement cost estimate	416.3
Cargo Claims And Other Insurance Related Amounts [Member]
LIability For Unpaid Claims And Claim Adjustment Expense, Adjustment Of Opening Balance [Roll Forward]
Undiscounted amount	$ 21.0	$ 20.4