Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010		Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Equipment rentals											$ 2,151	$ 1,834	$ 1,830
Sales of rental equipment											208	144	229
Sales of new equipment											84	78	86
Contractor supplies sales											85	95	121
Service and other revenues											83	86	92
Total revenues	746	[1]	713	629	523	597	[2]	605	557	478	2,611	2,237	2,358
Depreciation and amortization expense											480	449	474
Segment operating income	115	[1]	156	95	30	47	[2]	93	59	(2)	396	197	114
Capital expenditures											810	374	311
Total assets	4,143					3,693					4,143	3,693
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals											1,953	1,693	1,700
Sales of rental equipment											201	134	218
Sales of new equipment											77	72	81
Contractor supplies sales											79	89	114
Service and other revenues											79	83	89
Total revenues											2,389	2,071	2,202
Depreciation and amortization expense											448	426	449
Segment operating income											377	199	123
Capital expenditures											739	344	295
Total assets	3,776					3,458					3,776	3,458
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals											198	141	130
Sales of rental equipment											7	10	11
Sales of new equipment											7	6	5
Contractor supplies sales											6	6	7
Service and other revenues											4	3	3
Total revenues											222	166	156
Depreciation and amortization expense											32	23	25
Segment operating income											57	32	22
Capital expenditures											71	30	16
Total assets	367					235					367	235
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment operating income											$ 434	$ 231	$ 145

[1] During the fourth quarter of 2011, we recognized $19 of charges associated with the proposed RSC merger. Additionally, during the quarter, we closed 18 branches and recognized restructuring charges of $14. During the quarter, we also recognized asset impairment charges of $3 which are primarily reflected in non-rental depreciation and amortization and principally relate to write-offs of leasehold improvements and other fixed assets in connection with the consolidation of our branch network. In the quarter, we also purchased an aggregate of $32 of QUIPS for $32. In connection with this transaction, we retired $32 principal amount of our subordinated convertible debentures and recognized a loss of $1 in interest expense-subordinated convertible debentures, net, inclusive of the write-off of capitalized debt issuance costs. Interest expense, net for the fourth quarter of 2011 also includes a loss of $3 reflecting write-offs of debt issuance costs associated with the amendment of our ABL facility discussed above. During the quarter, we also recognized a benefit of $8 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves.

[2] During the fourth quarter of 2010, we repurchased or redeemed and subsequently retired an aggregate of $814 principal amount of our outstanding 7 3/4 percent Senior Subordinated Notes due 2013, 7 percent Senior Subordinated Notes due 2014 and 1 7/8 percent Convertible Senior Subordinated Notes due 2023. Interest expense, net for the fourth quarter of 2010 includes a charge of $25, representing the difference between the net carrying amount of these securities and the total purchase price of $827. The $25 charge includes a $4 write-off of a previously terminated derivative transaction. During the quarter, we also recognized restructuring charges of $15 related to the closure of 22 branches and reductions in headcount of approximately 100, and recognized asset impairment charges of $6. These asset impairment charges are primarily reflected in non-rental depreciation and amortization and principally relate to write-offs of leasehold improvement and other fixed assets in connection with the consolidation of our branch network. Additionally, the income tax provision (benefit) for the quarter includes a benefit of $7 related to a correction of a deferred tax asset recognized in prior periods. During the quarter, we also recognized a charge of $24 related to our provision for self-insurance reserves, comprised of $18 recorded in cost of equipment rentals, excluding depreciation, and $6 recorded in discontinued operation. The charge reflected recent adverse experience in our portfolio of automobile and general liability claims, as well as worker’s compensation claims. The discontinued operation component of the charge is reflected net of taxes in our consolidated statements of income.