INVESTMENTS - Details of Holdings of Perpetual Securities (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Investment Holdings [Line Items]
Amortized Cost	$ 62,963	$ 60,844
Fair Value	67,794	68,270
Unrealized Gain (Loss)	4,831	7,426
Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,841	2,440
Fair Value	1,947	2,669
Unrealized Gain (Loss)	106	229
Upper Tier II \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,217	1,554
Fair Value	1,265	1,645
Unrealized Gain (Loss)	48	91
Upper Tier II \| A \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	31	61
Fair Value	41	87
Unrealized Gain (Loss)	10	26
Upper Tier II \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,023	1,330
Fair Value	993	1,333
Unrealized Gain (Loss)	(30)	3
Upper Tier II \| BB or Lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	163	163
Fair Value	231	225
Unrealized Gain (Loss)	68	62
Tier I \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	441	703
Fair Value	477	793
Unrealized Gain (Loss)	36	90
Tier I \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	395	519
Fair Value	408	556
Unrealized Gain (Loss)	13	37
Tier I \| BB or Lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	46	184
Fair Value	69	237
Unrealized Gain (Loss)	23	53
Other subordinated - non-banks \| BB or Lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	183	183
Fair Value	205	231
Unrealized Gain (Loss)	$ 22	$ 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
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

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

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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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