Segment Information (Financial information by segment) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Equipment rentals									$ 4,941	$ 4,949	$ 4,819
Sales of rental equipment									496	538	544
Sales of new equipment									144	157	149
Contractor supplies sales									79	79	85
Service and other revenues									102	94	88
Total revenues	$ 1,523	$ 1,508	$ 1,421	$ 1,310	$ 1,523	$ 1,550	$ 1,429	$ 1,315	5,762	5,817	5,685
Depreciation and amortization expense									1,245	1,244	1,194
Gross profit	657	$ 656	$ 590	$ 500	648	$ 690	$ 618	$ 524	2,403	2,480	2,432
Capital expenditures									1,339	1,636	1,821
Total assets	11,988				12,083				11,988	12,083	12,129
General rentals
Segment Reporting Information [Line Items]
Equipment rentals									4,166	4,241	4,222
Sales of rental equipment									459	504	519
Sales of new equipment									128	137	113
Contractor supplies sales									64	67	73
Service and other revenues									91	83	75
Total revenues									4,908	5,032	5,002
Depreciation and amortization expense									1,066	1,071	1,060
Capital expenditures									1,189	1,439	1,594
Total assets	10,496				10,561				10,496	10,561	10,597
Trench, power and pump
Segment Reporting Information [Line Items]
Equipment rentals									775	708	597
Sales of rental equipment									37	34	25
Sales of new equipment									16	20	36
Contractor supplies sales									15	12	12
Service and other revenues									11	11	13
Total revenues									854	785	683
Depreciation and amortization expense									179	173	134
Capital expenditures									150	197	227
Total assets	$ 1,492				$ 1,522				1,492	1,522	1,532
Equipment rentals
Segment Reporting Information [Line Items]
Gross profit									2,089	2,147	2,092
Equipment rentals | General rentals
Segment Reporting Information [Line Items]
Gross profit									1,725	1,819	1,790
Equipment rentals | Trench, power and pump
Segment Reporting Information [Line Items]
Gross profit									$ 364	$ 328	$ 302