Fair Value Measurements (Details) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses	$ 2,371	$ 3,675
Revenue earning equipment, Trucks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses	1,228	1,882
Revenue earning equipment, Tractors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses	827	1,632
Revenue earning equipment, Trailers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses	316	161
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale at fair value	11,140	20,165
Fair Value, Inputs, Level 3 [Member] | Revenue earning equipment, Trucks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale at fair value	5,298	11,928
Fair Value, Inputs, Level 3 [Member] | Revenue earning equipment, Tractors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale at fair value	4,611	7,495
Fair Value, Inputs, Level 3 [Member] | Revenue earning equipment, Trailers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale at fair value	$ 1,231	$ 742