Segment Information (Reconciliation to consolidated totals) (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
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total equipment rentals gross profit	$ 648	$ 690	$ 618	$ 524	$ 707	$ 688	$ 589	$ 448	$ 2,480	$ 2,432	$ 1,987
Selling, general and administrative expenses									(714)	(758)	(642)
Merger related costs									26	(11)	(9)
Restructuring charge									(6)	1	(12)
Non-rental depreciation and amortization									(268)	(273)	(246)
Interest expense, net									(567)	(555)	(475)
Interest expense- subordinated convertible debentures									0	0	(3)
Other income, net									12	14	5
Income before provision for income taxes									963	850	605
Equipment rentals
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total equipment rentals gross profit									2,147	2,092	1,710
Other products and services
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total equipment rentals gross profit									$ 333	$ 340	$ 277