Goodwill and Other Intangible Assets (Other Intangible Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Net Amount	$ 875,000,000	$ 742,000,000
Amortization expense	173,000,000	174,000,000	$ 193,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2018	179,000,000
2019	158,000,000
2020	136,000,000
2021	115,000,000
2022	94,000,000
Thereafter	193,000,000
Net Amount	$ 875,000,000	$ 742,000,000
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	31 months	28 months
Gross Carrying Amount	$ 71,000,000	$ 70,000,000
Accumulated Amortization	62,000,000	57,000,000
Net Amount	9,000,000	13,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Net Amount	$ 9,000,000	$ 13,000,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	9 years	10 years
Gross Carrying Amount	$ 1,750,000,000	$ 1,465,000,000
Accumulated Amortization	884,000,000	737,000,000
Net Amount	866,000,000	728,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Net Amount	$ 866,000,000	$ 728,000,000
Trade names and associated trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period		4 months
Gross Carrying Amount		$ 80,000,000
Accumulated Amortization		79,000,000
Net Amount		1,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Net Amount		$ 1,000,000
NES Acquisition | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	9 years
Net Amount	$ 119,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Net Amount	$ 119,000,000
Neff Corporation | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-Average Remaining Amortization Period	10 years
Net Amount	$ 146,000,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Net Amount	146,000,000
NES and Neff Acquisitions
Finite-Lived Intangible Assets [Line Items]
Residual value, intangible assets	$ 0