Fair Value Measurements (Details) (USD $) | Sep. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 |
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Measurements, Nonrecurring [Member] |
| | | | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Trailers [Member] | Revenue earning equipment, Trailers [Member] | Revenue earning equipment, Trailers [Member] | Revenue earning equipment, Trailers [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Inputs, Level 3 [Member] |
| | | | | | | | | | | | | | | | | | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Trucks [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Tractors [Member] | Revenue earning equipment, Trailers [Member] | Revenue earning equipment, Trailers [Member] |
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis | ' | ' | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | |
Assets held for sale at fair value | ' | ' | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | $13,785,000 | [1] | $26,549,000 | [1] | $8,437,000 | [1] | $10,546,000 | [1] | $4,666,000 | [1] | $15,332,000 | [1] | $682,000 | [1] | $671,000 | [1] |
Total Losses | ' | ' | 2,377,000 | [1],[2] | 3,994,000 | [1],[2] | 8,567,000 | [1],[2] | 12,945,000 | [1],[2] | 1,527,000 | [1],[2] | 2,042,000 | [1],[2] | 4,981,000 | [1],[2] | 7,518,000 | [1],[2] | 530,000 | [1],[2] | 1,677,000 | [1],[2] | 2,824,000 | [1],[2] | 4,185,000 | [1],[2] | 320,000 | [1],[2] | 275,000 | [1],[2] | 762,000 | [1],[2] | 1,242,000 | [1],[2] | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | |
Fair Value Measurements (Textuals) (Abstract) | ' | ' | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | |
Fair value of total debt | $4,600,000,000 | $4,280,000,000 | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | | ' | |
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[1] | Represents the portion of all revenue earning equipment held for sale that is recorded at fair value, less costs to sell. |
[2] | Total losses represent fair value adjustments for all vehicles held for sale throughout the period for which fair value was less than carrying value. |