Revenue Earning Equipment (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue Earning Equipment [Line Items]
Cost	$ 10,643,152,000	$ 10,086,939,000
Accumulated Depreciation	3,648,704,000	3,596,102,000
Revenue earning equipment depreciation expense	961,000,000	884,000,000	867,000,000
Assets held under capital leases [Member]
Revenue Earning Equipment [Line Items]
Cost	48,000,000	54,000,000
Accumulated Depreciation	$ 22,000,000	$ 22,000,000