Goodwill and Other Intangible assets - Schedule of Other Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Intangible Assets [Line Items]
Intangible assets	$ 650	$ 644
Less accumulated amortization	(253)	(187)
Total	397	457
Customer Contracts And Customer Relationships [Member]
Goodwill And Intangible Assets [Line Items]
Intangible assets	426	392
Less accumulated amortization	(167)	(119)
Total	259	273
Covenants Not-to-Compete [Member]
Goodwill And Intangible Assets [Line Items]
Intangible assets	97	91
Less accumulated amortization	(54)	(41)
Total	43	50
Licenses Permits and Other [Member]
Goodwill And Intangible Assets [Line Items]
Intangible assets	127	161
Less accumulated amortization	(32)	(27)
Total	$ 95	$ 134