Earnings Per Share (Details) (USD $) In Millions, except Share data, 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	Dec. 31, 2013 Employee stock options and warrants [Member]	Dec. 31, 2012 Employee stock options and warrants [Member]	Dec. 31, 2011 Employee stock options and warrants [Member]	Dec. 31, 2013 Convertible subordinated notes - 1 7/8 percent [Member]	Dec. 31, 2012 Convertible subordinated notes - 1 7/8 percent [Member]	Dec. 31, 2011 Convertible subordinated notes - 1 7/8 percent [Member]	Dec. 31, 2013 4 percent Convertible Senior Notes [Member]	Dec. 31, 2012 4 percent Convertible Senior Notes [Member]	Dec. 31, 2011 4 percent Convertible Senior Notes [Member]	Dec. 31, 2013 Restricted stock units [Member]	Dec. 31, 2012 Restricted stock units [Member]	Dec. 31, 2011 Restricted stock units [Member]	Dec. 31, 2013 1 7/8 percent Convertible Senior Subordinated Notes [Member]	Dec. 31, 2012 1 7/8 percent Convertible Senior Subordinated Notes [Member]	Dec. 31, 2011 1 7/8 percent Convertible Senior Subordinated Notes [Member]	Dec. 31, 2013 4 percent Convertible Senior Notes [Member]	Dec. 31, 2012 4 percent Convertible Senior Notes [Member]	Dec. 31, 2011 4 percent Convertible Senior Notes [Member]	Nov. 30, 2009 4 percent Convertible Senior Notes [Member]
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount																	300,000		1,800,000		2,200,000
Numerator:
Net income	$ 140	[1]	$ 143	[1]	$ 83	[1]	$ 21	[1]	$ 41	[2]	$ 73	[2]	$ (52)	[2]	$ 13	[2]	$ 387	[1]	$ 75	[2]	$ 101
Convertible debt interest—1 7/8 percent notes																	0		0		0
Net income available to common stockholders																	$ 387		$ 75		$ 101
Denominator:
Denominator for basic earnings per share—weighted-average common shares																	93,436,000		82,960,000		62,184,000
Effect of dilutive securities, share-based payment arrangements																						504,000	720,000	1,037,000							582,000	536,000	581,000
Effect of dilutive securities, conversion of debt securities																									0		1,015,000	11,769,000	10,632,000	8,532,000
Denominator for diluted earnings per share—adjusted weighted-average common shares																	106,291,000		94,848,000		73,349,000
Stated interest rate																																		1.875%	1.875%	1.875%	4.00%	4.00%	4.00%	4.00%
Basic earnings per share (in dollars per share)	$ 1.49	[1]	$ 1.53	[1]	$ 0.89	[1]	$ 0.22	[1]	$ 0.45	[2]	$ 0.78	[2]	$ (0.63)	[2]	$ 0.21	[2]	$ 4.14	[1]	$ 0.91	[2]	$ 1.62
Diluted earnings per share (in dollars per share)	$ 1.31	[1],[3]	$ 1.35	[1],[3]	$ 0.78	[1],[3]	$ 0.19	[1],[3]	$ 0.40	[2],[3]	$ 0.70	[2],[3]	$ (0.63)	[2],[3]	$ 0.17	[2],[3]	$ 3.64	[1],[3]	$ 0.79	[2],[3]	$ 1.38

[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.

[3] Diluted earnings (loss) per share includes the after-tax impacts of the following: First Quarter Second Quarter Third Quarter Fourth Quarter Full YearFor the year ended December 31, 2013: RSC merger related costs (4)$(0.03) $(0.01) $— $— $(0.05)RSC merger related intangible asset amortization (5)(0.24) (0.24) (0.23) (0.24) (0.94)Impact on depreciation related to acquired RSC fleet and property and equipment (6)0.01 0.01 0.01 0.01 0.04Impact of the fair value mark-up of acquired RSC fleet and inventory (7)(0.08) (0.07) (0.05) (0.06) (0.25)Impact on interest expense related to fair value adjustment of acquired RSC indebtedness (9)0.01 0.01 0.01 0.01 0.04Restructuring charge (10)(0.04) (0.03) (0.01) — (0.07)Asset impairment charge (11)(0.01) (0.01) — — (0.02)Loss on extinguishment of debt securities, including subordinated convertible debentures(0.01) — (0.01) — (0.02)For the year ended December 31, 2012: RSC merger related costs (4)$(0.09) $(0.60) $(0.05) $(0.08) $(0.72)RSC merger related intangible asset amortization (5)— (0.21) (0.25) (0.25) (0.74)Impact on depreciation related to acquired RSC fleet and property and equipment (6)— 0.02 0.02 — 0.03Impact of the fair value mark-up of acquired RSC fleet and inventory (7)— (0.05) (0.09) (0.09) (0.24)Pre-close RSC merger related interest expense (8)(0.10) (0.12) — — (0.19)Impact on interest expense related to fair value adjustment of acquired RSC indebtedness (9)— 0.01 0.01 0.01 0.03Restructuring charge (10)— (0.39) (0.23) (0.03) (0.64)Asset impairment charge (11)— (0.02) (0.06) (0.01) (0.10)Loss on extinguishment of debt securities, including subordinated convertible debentures— — — (0.41) (0.45)Gain on sale of software subsidiary (12)— 0.07 — (0.01) 0.05