Depreciation of Revenue Earning Equipment and Lease Charges (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Depreciation of Revenue Earning Equipment and Lease Charges Disclosure [Abstract]
Depreciation of revenue earning equipment	$ 554,100,000	$ 528,100,000	$ 1,624,100,000	$ 1,399,900,000
Adjustment of depreciation upon disposal of revenue earning equipment	(12,700,000)	(30,900,000)	(93,300,000)	(93,300,000)
Rents paid for vehicles leased	19,100,000	26,100,000	63,600,000	72,400,000
Total	$ 560,529,000	$ 523,283,000	$ 1,594,396,000	$ 1,379,041,000