INVESTMENTS - Details of Holdings of Perpetual Securities (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Investment Holdings [Line Items]
Amortized Cost	$ 62,222	$ 60,844
Fair Value	67,403	68,270
Unrealized Gain (Loss)	5,181	7,426
Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	2,089	2,440
Fair Value	2,166	2,669
Unrealized Gain (Loss)	77	229
Upper Tier II: \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,337	1,554
Fair Value	1,369	1,645
Unrealized Gain (Loss)	32	91
Upper Tier II: \| A \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	61	61
Fair Value	87	87
Unrealized Gain (Loss)	26	26
Upper Tier II: \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,112	1,330
Fair Value	1,056	1,333
Unrealized Gain (Loss)	(56)	3
Upper Tier II: \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	164	163
Fair Value	226	225
Unrealized Gain (Loss)	62	62
Tier I: \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	568	703
Fair Value	595	793
Unrealized Gain (Loss)	27	90
Tier I: \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	522	519
Fair Value	524	556
Unrealized Gain (Loss)	2	37
Tier I: \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	46	184
Fair Value	71	237
Unrealized Gain (Loss)	25	53
Other subordinated - non-banks \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	184	183
Fair Value	202	231
Unrealized Gain (Loss)	$ 18	$ 48

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

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Amount of unrealized gain (loss) on investments in debt and equity securities classified as available-for-sale securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

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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.

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