Goodwill and Other Intangible Assets - Summary (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible assets
Goodwill	$ 6,247		$ 6,247	$ 6,215	$ 5,984
Increase in goodwill during the period			32
Goodwill impairment charges	34		34	12
Intangible assets	1,052		1,052	1,017
Less: Accumulated amortization	(505)		(505)	(426)
Total	547		547	591
Customer and Supplier Relationships [Member]
Intangible assets
Intangible assets	880		880	835
Less: Accumulated amortization	(422)		(422)	(342)
Total	458		458	493
Covenants Not To Compete [Member]
Intangible assets
Intangible assets	48		48	59
Less: Accumulated amortization	(21)		(21)	(31)
Total	27		27	28
Licenses Permits and Other [Member]
Intangible assets
Intangible assets	124		124	123
Less: Accumulated amortization	(62)		(62)	(53)
Total	62		62	70
Energy and Environmental Services [Member]
Intangible assets
Goodwill impairment charges	32		$ 34
Lamp Tracker Reporting Unit [Member]
Intangible assets
Goodwill impairment charges	$ 2	$ 10		$ 12