Segment Information (Geographic area information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals									$ 4,949	$ 4,819	$ 4,196
Sales of rental equipment									538	544	490
Sales of new equipment									157	149	104
Contractor supplies sales									79	85	87
Service and other revenues									94	88	78
Total revenues	$ 1,523	$ 1,550	$ 1,429	$ 1,315	$ 1,564	$ 1,544	$ 1,399	$ 1,178	5,817	5,685	4,955
Goodwill and other intangibles, net	4,148				4,378				4,148	4,378
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals									4,452	4,217	3,612
Sales of rental equipment									480	478	438
Sales of new equipment									137	124	82
Contractor supplies sales									69	70	70
Service and other revenues									80	73	62
Total revenues									5,218	4,962	4,264
Goodwill and other intangibles, net	3,838				4,014				3,838	4,014
Foreign (Canada)
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals									497	602	584
Sales of rental equipment									58	66	52
Sales of new equipment									20	25	22
Contractor supplies sales									10	15	17
Service and other revenues									14	15	16
Total revenues									599	723	$ 691
Goodwill and other intangibles, net	310				364				310	364
Rental equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	6,186				6,008				6,186	6,008
Rental equipment, net | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	5,657				5,399				5,657	5,399
Rental equipment, net | Foreign (Canada)
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	529				609				529	609
Property and equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	445				438				445	438
Property and equipment, net | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	399				395				399	395
Property and equipment, net | Foreign (Canada)
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 46				$ 43				$ 46	$ 43