Goodwill and Other Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Goodwill
Balance at the beginning of the period	$ 1,049,600,000	$ 1,044,800,000
Accumulated impairment losses at the beginning of the period	(721,000,000)	(721,000,000)
Net goodwill, balance at the beginning of the period	328,560,000	323,800,000
Goodwill acquired during the year	65,400,000	7,000,000
Adjustments to previously recorded purchase price allocation	(1,000,000)
Other changes during the year	(900,000)	(2,200,000)
Total changes in goodwill	63,500,000	4,800,000
Balance at the end of the period	1,113,100,000	1,049,600,000
Accumulated impairment losses at the end of the period	(721,000,000)	(721,000,000)
Net goodwill, balance at the end of the period	392,094,000	328,560,000
Car Rental
Goodwill
Balance at the beginning of the period	367,900,000	367,300,000
Accumulated impairment losses at the beginning of the period	(46,100,000)	(46,100,000)
Net goodwill, balance at the beginning of the period	321,800,000	321,200,000
Goodwill acquired during the year	53,100,000	2,700,000
Adjustments to previously recorded purchase price allocation	(900,000)
Other changes during the year	(800,000)	(2,100,000)
Total changes in goodwill	51,400,000	600,000
Balance at the end of the period	419,300,000	367,900,000
Accumulated impairment losses at the end of the period	(46,100,000)	(46,100,000)
Net goodwill, balance at the end of the period	373,200,000	321,800,000
Equipment Rental
Goodwill
Balance at the beginning of the period	681,700,000	677,500,000
Accumulated impairment losses at the beginning of the period	(674,900,000)	(674,900,000)
Net goodwill, balance at the beginning of the period	6,800,000	2,600,000
Goodwill acquired during the year	12,300,000	4,300,000
Adjustments to previously recorded purchase price allocation	(100,000)
Other changes during the year	(100,000)	(100,000)
Total changes in goodwill	12,100,000	4,200,000
Balance at the end of the period	693,800,000	681,700,000
Accumulated impairment losses at the end of the period	(674,900,000)	(674,900,000)
Net goodwill, balance at the end of the period	$ 18,900,000	$ 6,800,000