Percentage-of-Completion Contracts (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Disclosure Percentage Of Completion Contracts Additional Information [Abstract]
Costs and earnings in excess of billings related to contracts	$ 498	$ 507	$ 486
Billing in excess of costs and earnings on uncompleted contracts	$ 339us-gaap_BillingsInExcessOfCost	$ 363us-gaap_BillingsInExcessOfCost	$ 302us-gaap_BillingsInExcessOfCost

Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 35

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6802688&loc=d3e57807-111642

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

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-Section 45

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-URI http://asc.fasb.org/extlink&oid=6802688&loc=d3e57795-111642

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3(c)(3))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 912

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-URI http://asc.fasb.org/extlink&oid=6471842&loc=d3e55302-109406

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph c(2), c(3), c(4)

-Article 5

Name:	us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant