Retirement Benefits (Benefit Payments Of Expected Future Service ) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Year One	$ 620
Year Two	620
Year Three	645
Year Four	663
Year Five	699
Five Years Thereafter	4,011
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Year One	135
Year Two	131
Year Three	124
Year Four	117
Year Five	110
Five Years Thereafter	$ 450

The amount of the aggregate benefits expected to be paid in the five fiscal years thereafter (the aggregate amount of benefits expected to be paid in years 6 through 10 after the date of the latest statement of financial position).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

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