Interest Rate Hedging - Derivatives' Cash Flow Hedging Relationships (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of after tax of gain/(loss) recognized in Other Comprehensive Income on Derivatives (effective portion)	$ (3,015)	$ (431)
Pre-tax amount of gain/(loss) reclassified from Accumulated Other Comprehensive Income into Income (effective portion)	0
Interest Expense [Member] \| Forward Starting Interest Rate Swap Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of after tax of gain/(loss) recognized in Other Comprehensive Income on Derivatives (effective portion)	(3,015)	$ (431)
Pre-tax amount of gain/(loss) reclassified from Accumulated Other Comprehensive Income into Income (effective portion)	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624177-113959

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

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