Leases (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leased Assets [Line Items]
Impaired direct financing receivables	$ 0
Allowance for credit losses	288,000	501,000
Sale and leaseback of revenue earning equipment	125,825,000	0	130,184,000
Rent expense	147,000,000	152,000,000	146,000,000
Contingent rentals from operating leases	318,000,000	318,000,000	319,000,000
Direct Financing Leases [Member]
Operating Leased Assets [Line Items]
Contingent rental income	$ 11,000,000	$ 11,000,000	$ 11,000,000
Trucks and Tractors [Member]
Operating Leased Assets [Line Items]
Minimum lease term of revenue earning equipment	3 years
Maximum lease term of revenue earning equipment	7 years
Trailers [Member]
Operating Leased Assets [Line Items]
Maximum lease term of revenue earning equipment	10 years