Fair Value Disclosures - Investments in Certain Entities Calculate Net Asset Value per Share (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 647	$ 692
Total Unfunded Commitments	152	129
Equity Method, Hedge Funds/Funds of Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	230	277
Total Unfunded Commitments	$ 33	$ 39
Redemption Frequency (Daily)	21.00%	29.00%
Redemption Frequency (Monthly)	21.00%	29.00%
Redemption Frequency (Quarterly)	49.00%	48.00%
Redemption Frequency (Not Redeemable)	30.00%	23.00%
Equity Method, Hedge Funds/Funds of Hedge Funds [Member] \| Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period, days	30 days	1 day
Equity Method, Hedge Funds/Funds of Hedge Funds [Member] \| Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period, days	90 days	90 days
Equity Method, Hedge Funds/Funds of Hedge Funds [Member] \| Consolidated Variable Interest Entities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 58
Total Unfunded Commitments	$ 0
Equity Method, Hedge Funds/Funds of Hedge Funds [Member] \| Consolidated Variable Interest Entities [Member] \| Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period, days	90 days
Equity Method, Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 89	$ 107
Total Unfunded Commitments	67	61
Equity Method, Private Equity Funds [Member] \| Assets of Consolidated VIEs, [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		168
Total Unfunded Commitments		22
Equity Method, Private Equity Funds [Member] \| Consolidated Variable Interest Entities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	145	10
Total Unfunded Commitments	19	1
Equity Method, Real Estate Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	81	109
Total Unfunded Commitments	$ 28	$ 1
Redemption Frequency (Quarterly)	28.00%	19.00%
Redemption Frequency (Not Redeemable)	72.00%	81.00%
Redemption Notice Period, Not Redeemable	60 days	60 days
Equity Method, Other Types Of Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 44
Total Unfunded Commitments	$ 5
Redemption Frequency (Daily)	68.00%
Redemption Frequency (Monthly)	68.00%
Redemption Frequency (Not Redeemable)	32.00%
Equity Method, Other Types Of Investments [Member] \| Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period, days	3 days
Equity Method, Other Types Of Investments [Member] \| Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Redemption Notice Period, days	5 days
Equity Method, Deferred Compensation Plan Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value		$ 21
Total Unfunded Commitments		$ 5

Fair Value Measured Recurring Basis Using Net Asset Per Share Value Redemption Frequency (daily)

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Fair Value Measured Recurring Basis Using Net Asset Per Share Value Redemption Frequency (monthly)

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Fair value measured recurring basis using net asset per share value redemption frequency not redeemable.

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Fair Value Measured Recurring Basis Using Net Asset Per Share Value Redemption Frequency (quarterly)

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Fair Value Measured Recurring Basis Using Net Asset Per Share Value Redemption Notice Period Not Redeemable

+ References

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Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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Notice period the entity is required to deliver before it can redeem an investment calculated using net asset value per share, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, investments calculated by per unit, per membership interest, other equity or ownership interest and alternative investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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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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- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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