Fair Value Measurements (Details 1) (USD $)			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member] Revenue earning equipment, Trailers [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis
Assets held for sale at fair value																			$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 26,549,000	$ 21,017,000	$ 10,546,000	$ 11,994,000	$ 15,332,000	$ 8,616,000	$ 671,000	$ 407,000
Total Losses			3,994,000	5,161,000	12,945,000	12,975,000	2,042,000	3,664,000	7,518,000	9,153,000	1,677,000	1,097,000	4,185,000	2,639,000	275,000	400,000	1,242,000	1,183,000
Fair Value Measurements (Textuals) (Abstract)
Fair value of total debt	$ 4,140,000,000	$ 3,990,000,000