Preliminary Allocation Purchase Price Intangible Assets (Detail) (Oakleaf [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization	$ 87
Total intangible assets subject to amortization, weighted average amortization period	10 years 6 months
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization	74
Total intangible assets subject to amortization, weighted average amortization period	10 years
Vendor relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization	4
Total intangible assets subject to amortization, weighted average amortization period	10 years
Trademarks [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization	$ 9
Total intangible assets subject to amortization, weighted average amortization period	15 years