Earnings Per Share (Details) (USD $)
In Millions, except Share data, unless otherwise specified
 3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]                      
Antidilutive securities excluded from computation of earnings per share, amount                   300,000 1,800,000
Numerator:                      
Net income available to common stockholders                 $ 540 $ 387 $ 75
Denominator:                      
Denominator for basic earnings per share—weighted-average common shares                 97,489,000 93,436,000 82,960,000
Effect of dilutive securities:                      
Denominator for diluted earnings per share—adjusted weighted-average common shares                 104,956,000 106,291,000 94,848,000
Basic earnings per share (in dollars per share) $ 1.96 [1] $ 1.95 [1] $ 0.98 [1] $ 0.63 [1] $ 1.49 [2] $ 1.53 [2] $ 0.89 [2] $ 0.22 [2] $ 5.54 [1] $ 4.14 [2] $ 0.91
Diluted earnings per share (in dollars per share) $ 1.88 [1],[3] $ 1.84 [1],[3] $ 0.90 [1],[3] $ 0.56 [1],[3] $ 1.31 [2],[3] $ 1.35 [2],[3] $ 0.78 [2],[3] $ 0.19 [2],[3] $ 5.15 [1],[3] $ 3.64 [2],[3] $ 0.79
4 percent Convertible Senior Notes                      
Effect of dilutive securities:                      
Effect of dilutive securities, conversion of debt securities                 6,386,000 11,769,000 10,632,000
Stated interest rate 4.00%       4.00%       4.00% 4.00% 4.00%
Employee stock options and warrants                      
Effect of dilutive securities:                      
Effect of dilutive securities, share-based payment arrangements                 394,000 504,000 720,000
Restricted stock units                      
Effect of dilutive securities:                      
Effect of dilutive securities, share-based payment arrangements                 687,000 582,000 536,000
[1] The fourth quarter of 2014 includes an increase in bad debt expense of $8 as compared to the fourth quarter of 2013 primarily due to improved receivable aging which reduced the expense in the fourth quarter of 2013. Additionally, the fourth quarter of 2014 includes an increase in stock compensation, net of $14 as compared to the fourth quarter of 2013 primarily due to improved profitability which resulted in increased performance based stock compensation.
[2] 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 $3 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves.
[3] Diluted earnings per share includes the after-tax impacts of the following: First Quarter Second Quarter Third Quarter Fourth Quarter Full YearFor the year ended December 31, 2014: Merger related costs (4)$(0.01) $(0.05) $(0.02) $0.02 $(0.06)Merger related intangible asset amortization (5)(0.22) (0.29) (0.29) (0.30) (1.10)Impact on depreciation related to acquired RSC fleet and property and equipment (6)— 0.01 0.01 0.01 0.03Impact of the fair value mark-up of acquired RSC fleet (7)(0.05) (0.06) (0.05) (0.05) (0.21)Impact on interest expense related to fair value adjustment of acquired RSC indebtedness (8)0.01 0.01 — 0.01 0.03Restructuring charge (9)(0.01) 0.01 0.01 — 0.01Loss on extinguishment of debt securities(0.06) (0.38) (0.02) — (0.46)For the year ended December 31, 2013: Merger related costs (4)$(0.03) $(0.01) $— $— $(0.05)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 (7)(0.08) (0.07) (0.05) (0.06) (0.25)Impact on interest expense related to fair value adjustment of acquired RSC indebtedness (8)0.01 0.01 0.01 0.01 0.04Restructuring charge (9)(0.04) (0.03) (0.01) — (0.07)Asset impairment charge (10)(0.01) (0.01) — — (0.02)Loss on extinguishment of debt securities, including subordinated convertible debentures(0.01) — (0.01) — (0.02)