Debt and Subordinated Convertible Debentures (Schedule of long-term debt instruments) (Details) (USD $)	3 Months Ended					3 Months Ended											1 Months Ended		3 Months Ended																																															0 Months Ended	1 Months Ended			0 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013		Mar. 31, 2014 Accounts Receivable Securitization Facility	Mar. 31, 2014 $2.3 billion ABL Facility	Mar. 31, 2014 5 3/4 percent Senior Secured Notes	Mar. 31, 2014 10 1/4 percent Senior Notes	Jan. 31, 2014 10 1/4 percent Senior Notes	Mar. 31, 2014 9 1/4 percent Senior Notes	Mar. 31, 2014 7 3/8 percent Senior Notes	Mar. 31, 2014 8 3/8 percent Senior Subordinated Notes	Mar. 31, 2014 8 1/4 percent Senior Notes	Mar. 31, 2014 7 5/8 percent Senior Notes	Mar. 31, 2014 6 1/8 percent Senior Notes	Mar. 31, 2014 Add-on to 6 1/8 percent Senior Notes	Mar. 31, 2014 5 3/4 percent Senior Notes	Mar. 31, 2014 Convertible subordinated notes—4 percent	Nov. 30, 2009 Convertible subordinated notes—4 percent	Mar. 31, 2014 Subsidiaries Accounts Receivable Securitization Facility		Dec. 31, 2013 Subsidiaries Accounts Receivable Securitization Facility		Mar. 31, 2014 Subsidiaries $2.3 billion ABL Facility		Dec. 31, 2013 Subsidiaries $2.3 billion ABL Facility		Mar. 31, 2014 Subsidiaries 5 3/4 percent Senior Secured Notes	Dec. 31, 2013 Subsidiaries 5 3/4 percent Senior Secured Notes	Mar. 31, 2014 Subsidiaries 10 1/4 percent Senior Notes		Dec. 31, 2013 Subsidiaries 10 1/4 percent Senior Notes		Mar. 31, 2014 Subsidiaries 9 1/4 percent Senior Notes		Dec. 31, 2013 Subsidiaries 9 1/4 percent Senior Notes		Mar. 31, 2014 Subsidiaries 7 3/8 percent Senior Notes	Dec. 31, 2013 Subsidiaries 7 3/8 percent Senior Notes	Mar. 31, 2014 Subsidiaries 8 3/8 percent Senior Subordinated Notes	Dec. 31, 2013 Subsidiaries 8 3/8 percent Senior Subordinated Notes	Mar. 31, 2014 Subsidiaries 8 1/4 percent Senior Notes	Dec. 31, 2013 Subsidiaries 8 1/4 percent Senior Notes	Mar. 31, 2014 Subsidiaries 7 5/8 percent Senior Notes	Dec. 31, 2013 Subsidiaries 7 5/8 percent Senior Notes	Mar. 31, 2014 Subsidiaries 6 1/8 percent Senior Notes		Dec. 31, 2013 Subsidiaries 6 1/8 percent Senior Notes		Mar. 31, 2014 Subsidiaries 5 3/4 percent Senior Notes		Dec. 31, 2013 Subsidiaries 5 3/4 percent Senior Notes		Mar. 31, 2014 Subsidiaries Capital leases	Dec. 31, 2013 Subsidiaries Capital leases	Mar. 31, 2014 Subsidiaries Total URNA and subsidiaries debt	Dec. 31, 2013 Subsidiaries Total URNA and subsidiaries debt	Mar. 31, 2014 Parent Company	Dec. 31, 2013 Parent Company	Mar. 31, 2014 Parent Company Convertible subordinated notes—4 percent		Dec. 31, 2013 Parent Company Convertible subordinated notes—4 percent		Apr. 16, 2014 Subsequent Event 9 1/4 percent Senior Notes	Apr. 16, 2014 Subsequent Event Convertible subordinated notes—4 percent	Mar. 31, 2014 On or after May 15, 2019 5 3/4 percent Senior Notes	Mar. 31, 2014 On or after May 15, 2022 5 3/4 percent Senior Notes	Jan. 31, 2014 Interest Expense 10 1/4 percent Senior Notes	Apr. 16, 2014 Interest Expense Subsequent Event 9 1/4 percent Senior Notes
Debt Instrument
Total debt	$ 7,039,000,000			$ 7,173,000,000																	$ 140,000,000	[1]	$ 430,000,000	[1]	$ 135,000,000	[2]	$ 1,106,000,000	[2]	$ 750,000,000	$ 750,000,000	$ 0	[3]	$ 220,000,000	[3]	$ 494,000,000	[4]	$ 494,000,000	[4]	$ 750,000,000	$ 750,000,000	$ 750,000,000	$ 750,000,000	$ 691,000,000	$ 692,000,000	$ 1,325,000,000	$ 1,325,000,000	$ 953,000,000	[5]	$ 400,000,000	[5]	$ 850,000,000	[6]	$ 0	[6]	$ 112,000,000	$ 120,000,000	$ 6,950,000,000	$ 7,037,000,000			$ 89,000,000	[7]	$ 136,000,000	[7]
Less short-term portion	(265,000,000)	[8]		(604,000,000)	[8]																																																						(89,000,000)	(136,000,000)
Total long-term debt	6,774,000,000			6,569,000,000																																																							0	0
Stated interest rate	4.00%							5.75%	10.25%		9.25%	7.375%	8.375%	8.25%	7.625%	6.125%		5.75%	4.00%
Maximum borrowing capacity																									2,300,000,000.0
Unused borrowing capacity under facility						313,000,000	2,100,000,000
Interest rate at end of period						0.80%	3.40%
Average outstanding amount under facility						331,000,000
Weighted average interest rate						0.80%	2.50%
A/R Securitization maximum month-end outstanding amount						427,000,000
Collateral amount						453,000,000
Letters of credit outstanding							52,000,000
Average outstanding amount							873,000,000
ABL Facility maximum month-end outstanding amount							1,300,000,000
Debt redemption, call premium amount										26,000,000																																																							52,000,000
Face amount																925,000,000	525,000,000	850,000,000	100,000,000	173,000,000
Unamortized premium																	28,000,000
Effective interest rate																5.70%			6.60%
Proceeds from debt	2,398,000,000		631,000,000														546,000,000	837,000,000
Debt redemption price, percentage																		101.00%																																																	102.875%	100.00%
Unamortized discount																			11,000,000
Extinguishment of debt, amount																			56,000,000																																															4,000,000
Gain (loss) on extinguishment of debt securities	$ (11,000,000)		$ 0																$ (5,000,000)																																																		$ (6,000,000)	$ (65,000,000)
Convertible, conversion price (in dollars per share)																			$ 11.11

[1] At March 31, 2014, $313 was available under our accounts receivable securitization facility. The interest rate applicable to the accounts receivable securitization facility was 0.8 percent at March 31, 2014. During the three months ended March 31, 2014, the monthly average amount outstanding under the accounts receivable securitization facility was $331, and the weighted-average interest rate thereon was 0.8 percent. The maximum month-end amount outstanding under the accounts receivable securitization facility during the three months ended March 31, 2014 was $427. Borrowings under the accounts receivable securitization facility are permitted only to the extent that the face amount of the receivables in the collateral pool, net of applicable reserves, exceeds the outstanding loans. As of March 31, 2014, there were $453 of receivables, net of applicable reserves, in the collateral pool.

[2] At March 31, 2014, $2.1 billion was available under our ABL facility, net of $52 of letters of credit. The interest rate applicable to the ABL facility was 3.4 percent at March 31, 2014. During the three months ended March 31, 2014, the monthly average amount outstanding under the ABL facility was $873, and the weighted-average interest rate thereon was 2.5 percent. The maximum month-end amount outstanding under the ABL facility during the three months ended March 31, 2014 was $1.3 billion.

[3] In January 2014, we redeemed all of our 10 1/4 percent Senior Notes. We paid a call premium of $26 in connection with the redemption, and recognized a loss of approximately $6 in interest expense, net upon redemption. The loss represented the difference between the net carrying amount and the total purchase price of the notes.

[4] As discussed in note 10 to the condensed consolidated financial statements, in March 2014, we announced that we were acquiring assets of the following four entities: National Pump & Compressor, Ltd., Canadian Pump and Compressor Ltd., GulfCo Industrial Equipment, LP and LD Services, LLC (collectively “National Pump”). Using proceeds from debt issued contemporaneous with the National Pump acquisition, as discussed below, and cash on hand, we redeemed all the outstanding 9 1/4 percent Senior Notes in April 2014. We paid a call premium of approximately $52 in connection with the redemption and recognized a loss of approximately $65 in interest expense upon redemption. The loss represented the difference between the net carrying amount and the total purchase price of the notes.

[5] Contemporaneous with the National Pump acquisition described in note 10 to the condensed consolidated financial statements, in March 2014, URNA issued $525 principal amount of 6 1/8 percent Senior Notes as an add on to our existing 6 1/8 percent Senior Notes. The net proceeds from the issuance were $546 (after deducting offering expenses). The newly issued notes have identical terms, and are fungible, with the 6 1/8 percent Senior Notes outstanding at December 31, 2013. The difference between the carrying value of the 6 1/8 percent Senior Notes and the $925 principal amount relates to the $28 unamortized portion of the original issue premium recognized in conjunction with the March 2014 issuance, which is being amortized through the maturity date in 2023. The effective interest rate on the 6 1/8 percent Senior Notes is 5.7 percent.

[6] In connection with the National Pump acquisition described in note 10 to the condensed consolidated financial statements, in March 2014, URNA issued $850 principal amount of 5 3/4 percent Senior Notes which are due November 15, 2024. The net proceeds from the issuance were $837 (after deducting offering expenses). The net proceeds were used to finance in part the cash purchase price of the National Pump acquisition which closed in April 2014. The 5 3/4 percent Senior Notes are unsecured and are guaranteed by Holdings and, subject to limited exceptions, URNA's domestic subsidiaries. The 5 3/4 percent Senior Notes may be redeemed on or after May 15, 2019, at specified redemption prices that range from 102.875 percent in the 12-month period commencing on May 15, 2019, to 100 percent in the 12-month period commencing on May 15, 2022 and thereafter, plus accrued and unpaid interest. The indenture governing the 5 3/4 percent Senior Notes contains certain restrictive covenants, including, among others, limitations on (1) liens; (2) additional indebtedness; (3) mergers, consolidations and acquisitions; (4) sales, transfers and other dispositions of assets; (5) loans and other investments; (6) dividends and other distributions, stock repurchases and redemptions and other restricted payments; (7) restrictions affecting subsidiaries; (8) transactions with affiliates; and (9) designations of unrestricted subsidiaries, as well as a requirement to timely file periodic reports with the SEC. Each of these covenants is subject to important exceptions and qualifications that would allow URI to engage in these activities under certain conditions. The indenture also requires that, in the event of a change of control (as defined in the indenture), URI must make an offer to purchase all of the then-outstanding 5 3/4 percent Senior Notes tendered at a purchase price in cash equal to 101 percent of the principal amount thereof, plus accrued and unpaid interest, if any, thereon.

[7] The difference between the March 31, 2014 carrying value of the 4 percent Convertible Senior Notes and the $100 principal amount reflects the $11 unamortized portion of the original issue discount recognized upon issuance of the notes, which is being amortized through the maturity date of November 15, 2015. Because the 4 percent Convertible Senior Notes were redeemable at March 31, 2014, an amount equal to the $11 unamortized portion of the original issue discount is separately classified in our condensed consolidated balance sheets and referred to as “temporary equity.” During the three months ended March 31, 2014, $56 of our 4 percent Convertible Notes were redeemed. We recognized a loss of approximately $5 in interest expense, net upon redemption. The loss represented the difference between the net carrying amount and the fair value of the debt component of the notes. Based on the price of our common stock during the first quarter of 2014, holders of the 4 percent Convertible Senior Notes have the right to redeem the notes during the second quarter of 2014 at a conversion price of $11.11 per share of common stock. Since April 1, 2014 (the beginning of the second quarter), $4 of the 4 percent Convertible Senior Notes were redeemed.

[8] As of March 31, 2014, our short-term debt primarily reflects $140 of borrowings under our accounts receivable securitization facility and $89 of 4 percent Convertible Senior Notes. The 4 percent Convertible Senior Notes mature in November 2015, but are reflected as short-term debt because they are redeemable at March 31, 2014.