Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Equipment rentals																	$ 4,196		$ 3,455		$ 2,151
Sales of rental equipment																	490		399		208
Sales of new equipment																	104		93		84
Contractor supplies sales																	87		87		85
Service and other revenues																	78		83		83
Total revenues	1,338	[1]	1,311	[1]	1,206	[1]	1,100	[1]	1,249	[2]	1,219	[2]	993	[2]	656	[2]	4,955	[1]	4,117	[2]	2,611
Depreciation and amortization expense																	1,098		897		480
Equipment rentals gross profit																	1,710		1,364		736
Capital expenditures																	1,684		1,369		810
Total assets	11,231								11,026								11,231		11,026
Operating Segments [Member] | General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals																	3,869		3,188		1,953
Sales of rental equipment																	474		387		201
Sales of new equipment																	97		86		77
Contractor supplies sales																	79		80		79
Service and other revenues																	72		79		79
Total revenues																	4,591		3,820		2,389
Depreciation and amortization expense																	1,038		850		448
Equipment rentals gross profit																	1,557		1,239		643
Capital expenditures																	1,556		1,285		739
Total assets	10,677								10,545								10,677		10,545
Operating Segments [Member] | Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals																	327		267		198
Sales of rental equipment																	16		12		7
Sales of new equipment																	7		7		7
Contractor supplies sales																	8		7		6
Service and other revenues																	6		4		4
Total revenues																	364		297		222
Depreciation and amortization expense																	60		47		32
Equipment rentals gross profit																	153		125		93
Capital expenditures																	128		84		71
Total assets	$ 554								$ 481								$ 554		$ 481

[1] The fourth quarter of 2013 includes a reduction in bad debt expense of $17 as compared to the fourth quarter of 2012 primarily due to improved receivable aging. In the fourth quarter of 2013, we recognized a benefit of $3 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves.

[2] During the fourth quarter of 2012, we recognized $13 of charges associated with the RSC acquisition. Additionally, during the quarter, we recognized restructuring charges of $6, primarily reflecting branch closure charges associated with the RSC acquisition. During the quarter, we also recognized asset impairment charges of $2 which are primarily reflected in non-rental depreciation and amortization and principally relate to write-offs of leasehold improvements and other fixed assets. During the fourth quarter of 2012, we redeemed our 10 7/8 percent Senior Notes and all of our outstanding 1 7/8 percent Convertible Senior Subordinated Notes were converted. Upon redemption/conversion, we recognized a loss of $72 in interest expense, net. The loss represents the difference between the net carrying amount and the total purchase/conversion price of these securities. During the quarter, we also recognized a benefit of $6 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves. Additionally, operating income for the fourth quarter 2012 included $8 of costs, in the aggregate, primarily related to the merger, which should have been recognized in the second and third quarters of 2012. There was no impact on 2012 full year operating income.