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, 2012	Dec. 31, 2011	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2011 Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2011 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, 2011 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trucks [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2011 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, 2011 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Tractors [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2011 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, 2011 Fair Value, Measurements, Nonrecurring [Member] Revenue earning equipment, Trailers [Member]	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2011 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] Revenue earning equipment, Trucks [Member]	Sep. 30, 2011 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, Tractors [Member]	Sep. 30, 2011 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, Trailers [Member]	Sep. 30, 2011 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 2 [Member]	Sep. 30, 2011 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] Revenue earning equipment, Trucks [Member]	Sep. 30, 2011 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, Tractors [Member]	Sep. 30, 2011 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, Trailers [Member]	Sep. 30, 2011 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 3 [Member]	Sep. 30, 2011 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] Revenue earning equipment, Trucks [Member]	Sep. 30, 2011 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, Tractors [Member]	Sep. 30, 2011 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, Trailers [Member]	Sep. 30, 2011 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	$ 21,017,000	$ 8,730,000	$ 11,994,000	$ 6,401,000	$ 8,616,000	$ 1,972,000	$ 407,000	$ 357,000
Total Losses			5,161,000	2,005,000	12,975,000	6,067,000	3,664,000	1,275,000	9,153,000	3,875,000	1,097,000	425,000	2,639,000	1,377,000	400,000	305,000	1,183,000	815,000
Fair Value Measurements (Textuals) (Abstract)
Fair value of total debt	$ 4,060,000,000	$ 3,510,000,000