Restructuring (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended		47 Months Ended	3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended					3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended	9 Months Ended
	Sep. 30, 2011 Employee D M plan	Jun. 30, 2011 Employee	Mar. 31, 2011 Employee	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010 Employee	Sep. 30, 2011 Involuntary termination benefits M	Sep. 30, 2010 Involuntary termination benefits	Sep. 30, 2011 Involuntary termination benefits M	Sep. 30, 2010 Involuntary termination benefits	Sep. 30, 2011 Pension and post retirement expense	Sep. 30, 2010 Pension and post retirement expense	Sep. 30, 2011 Consultant costs	Sep. 30, 2010 Consultant costs	Sep. 30, 2011 Consultant costs	Sep. 30, 2010 Consultant costs	Sep. 30, 2011 Asset writedowns	Sep. 30, 2010 Asset writedowns	Sep. 30, 2011 Asset writedowns	Sep. 30, 2010 Asset writedowns	Sep. 30, 2011 Facility closure and lease obligation costs	Sep. 30, 2010 Facility closure and lease obligation costs	Sep. 30, 2011 Facility closure and lease obligation costs	Sep. 30, 2010 Facility closure and lease obligation costs	Sep. 30, 2011 Facility closures	Sep. 30, 2011 FAS 88 pension adjustment	Sep. 30, 2011 Involuntary benefits	Sep. 30, 2011 Relocation costs and temporary labor costs	Sep. 30, 2010 Relocation costs and temporary labor costs	Sep. 30, 2011 Relocation costs and temporary labor costs	Sep. 30, 2010 Relocation costs and temporary labor costs	Sep. 30, 2010 Other-	Sep. 30, 2011 Other-	Sep. 30, 2010 Other-	Sep. 30, 2011 Foreign currency translation	Sep. 30, 2011 Direct operating	Sep. 30, 2010 Direct operating	Sep. 30, 2011 Direct operating	Sep. 30, 2010 Direct operating	Sep. 30, 2011 Selling, general and administrative	Sep. 30, 2010 Selling, general and administrative	Sep. 30, 2011 Selling, general and administrative	Sep. 30, 2010 Selling, general and administrative	Sep. 30, 2011 Car Rental	Sep. 30, 2010 Car Rental	Sep. 30, 2011 Car Rental	Sep. 30, 2010 Car Rental	Dec. 31, 2008 Car Rental Location	Sep. 30, 2011 Equipment Rental	Jun. 30, 2011 Equipment Rental Branch	Sep. 30, 2010 Equipment Rental	Sep. 30, 2011 Equipment Rental	Sep. 30, 2010 Equipment Rental	Dec. 31, 2008 Equipment Rental Branch	Sep. 30, 2011 Other	Sep. 30, 2011 Other reconciling items	Sep. 30, 2010 Other reconciling items
Restructuring details
Number of off-airport locations closed																																																	250
Number of branches in U.S. equipment rental segment closed																																																			12				22
Number of employees impacted	170	50	100				8,500
Restructuring charges incurred to date					$ 514.6																																										$ 247.0						$ 213.8			$ 53.8
Restructuring charges	1.9			14.6	40.4	45.5		2.4	2.7	6.8	7.5	0.3	0.6	0.3	0.2	0.6	0.9	(0.5)	5.0	22.8	19.5	(0.4)	5.3	9.6	11.9				0.1	1.3	0.1	3.8	0.1	0.2	1.3		0.7	12.5	35.3	37.7	1.2	2.1	5.1	7.8	2.8	4.0	7.3	13.4		(0.9)		10.6	32.7	31.4			0.4	0.7
Increase (decrease) in diluted earnings per share during the reporting period due to the after-tax effect of the restructuring charges (in dollars per share)	$ 0.00			$ (0.03)	$ (0.06)
Increase (decrease) in diluted loss per share during the reporting period due to the after-tax effect of the restructuring charges (in dollars per share)						$ 0.08
Expected duration for payment of restructuring obligations (in months)								12		12
Restructuring reserve
Restructuring reserve, Balance at beginning of period			17.5		17.5					6.3		0.2				0.1																		10.9
Charges incurred					40.4					6.8		0.3				0.6																		32.7
Cash payments					(12.9)					(10.7)						(0.5)																		(1.7)
Other					(30.5)					0.9		(0.3)								(22.8)						(8.3)	(0.3)	0.8						(31.1)		0.2
Restructuring reserve, Balance at end of period	$ 14.5				$ 14.5		$ 17.5	$ 3.3		$ 3.3		$ 0.2		$ 0.2		$ 0.2																		$ 10.8