Assets measured at NAV [Line Items]

No definition available.

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

No definition available.

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

No definition available.

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- Definition

Notice period in days for redemption of investment funds alternative investments (employ various investment strategies such as long/short equity and arbitrage/distressed.)

+ References

No definition available.

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- Definition

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226003-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

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- Definition

Amount of long-term investments classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Fair Value Measurements (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value Measurements Of Financial Instruments [Line Items]
Other Long-term Investments	$ 4,400		$ 4,400		$ 3,291
Fair Value, Level 1 to Level 2 transfers, Amount	0	$ 0	0	$ 0
Fair Value, Level 2 to Level 1 Transfers, Amount	0	$ 0	$ 0	$ 0
Minimum [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice Period For Redemption For Alternative Investments Investment Funds			5 days
Maximum [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice Period For Redemption For Alternative Investments Investment Funds			120 days
Equity Option [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Derivative Asset, Fair Value, Gross Liability	$ 0		$ 0