Commitments and Contingencies (Insurance and Legal) (Details)	1 Months Ended
	May. 31, 2007 entity	Dec. 25, 2015 USD ($)
Insurance
Non-catastrophic property deductible		$ 25,000,000
Casualty and catastrophic property deductible		50,000,000
Pending Litigation [Member]
Loss Contingency, Estimate [Abstract]
Minimum range of possible loss for legal proceedings		2,000,000
Maximum range of possible loss for legal proceedings		$ 78,000,000
Fuel Surcharge Antitrust Litigation [Member]
Loss Contingency, Estimate [Abstract]
Number of other U.S.-based entities mentioned in class action lawsuit | entity	3