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Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Millions, unless otherwise specified	0 Months Ended	1 Months Ended
	Oct. 11, 2013	Aug. 31, 2012	Jan. 30, 2015	Jan. 31, 2014	Jan. 31, 2013
Business Combination Allocation of Purchase Price [Line Items]
Goodwill			$ 1,207us-gaap_Goodwill	$ 1,693us-gaap_Goodwill	$ 1,693us-gaap_Goodwill
Plainfield Renewal Energy Holdings LLC
Business Combination Allocation of Purchase Price [Line Items]
Property, plant and equipment	248
Other assets	8
Notes payable assumed (net of debt discount)	(148)
Total identifiable net assets acquired	108
Intangible assets	3
Total purchase consideration	111
maxIT Healthcare Holdings Inc.
Business Combination Allocation of Purchase Price [Line Items]
Cash		9
Receivables		50
Other assets		24
Accounts payable, accrued liabilities and accrued payroll and employee benefits		(21)
Deferred tax liabilities, net		(24)
Total identifiable net assets acquired		38
Goodwill		395
Intangible assets		72
Total purchase consideration		$ 505