Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valuation and Qualifying Accounts (Textual) [Abstract]
Benefit (charge) within operating expense	$ 1,000,000	$ 4,000,000	$ (3,000,000)
Accounts receivable allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	14,489,000	13,867,000	13,808,000
Charged to Earnings	10,478,000	7,466,000	4,757,000
Transferred from to Other Accounts	0	0	0
Deductions	(9,538,000)	(6,844,000)	(4,698,000)
Ending Balance	15,429,000	14,489,000	13,867,000
Direct finance lease allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	903,000	784,000	813,000
Charged to Earnings	812,000	867,000	399,000
Transferred from to Other Accounts	0	0	0
Deductions	(1,012,000)	(748,000)	(428,000)
Ending Balance	703,000	903,000	784,000
Self-insurance accruals [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	253,424,000	243,248,000	242,905,000
Charged to Earnings	272,357,000	217,980,000	201,236,000
Transferred from to Other Accounts	57,285,000	54,833,000	45,470,000
Deductions	(303,909,000)	(262,637,000)	(246,363,000)
Ending Balance	279,157,000	253,424,000	243,248,000
Reserve For Residual Value Guarantees [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	4,218,000	4,497,000	4,049,000
Charged to Earnings	179,000	347,000	1,643,000
Transferred from to Other Accounts	0	0	0
Deductions	(2,762,000)	(626,000)	(1,195,000)
Ending Balance	1,635,000	4,218,000	4,497,000
Valuation allowance on deferred tax assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	41,324,000	39,216,000	36,573,000
Charged to Earnings	1,061,000	672,000	978,000
Transferred from to Other Accounts	0	0	0
Deductions	(4,203,000)	1,436,000	1,665,000
Ending Balance	$ 38,182,000	$ 41,324,000	$ 39,216,000