INVESTMENTS - Details of Holdings of Perpetual Securities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Investment Holdings [Line Items]
Amortized Cost	$ 61,937	$ 60,844
Fair Value	69,907us-gaap_AvailableForSaleSecurities	68,270us-gaap_AvailableForSaleSecurities
Unrealized Gain (Loss)	7,970	7,426
Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	2,309	2,440
Fair Value	2,560	2,669
Unrealized Gain (Loss)	251	229
Upper Tier II: \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,434	1,554
Fair Value	1,555	1,645
Unrealized Gain (Loss)	121	91
Upper Tier II: \| A \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	61	61
Fair Value	88	87
Unrealized Gain (Loss)	27	26
Upper Tier II: \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	1,209	1,330
Fair Value	1,235	1,333
Unrealized Gain (Loss)	26	3
Upper Tier II: \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	164	163
Fair Value	232	225
Unrealized Gain (Loss)	68	62
Tier I: \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	692	703
Fair Value	786	793
Unrealized Gain (Loss)	94	90
Tier I: \| BBB \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	521	519
Fair Value	561	556
Unrealized Gain (Loss)	40	37
Tier I: \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	171	184
Fair Value	225	237
Unrealized Gain (Loss)	54	53
Other subordinated - non-banks \| BB or lower \| Perpetual securities
Investment Holdings [Line Items]
Amortized Cost	183	183
Fair Value	219	231
Unrealized Gain (Loss)	$ 36	$ 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=28360136&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=6871852&loc=d3e26610-111562

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- Definition

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)

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

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- Definition

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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