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Investments (Available-For-Sale In Consolidated Investment Portfolio) (Detail) (USD $) In Millions, unless otherwise specified | Sep. 30, 2012 | Dec. 31, 2011
--- | --- | ---
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | $ 6,729 |  | $ 9,025 |
Gross Unrealized Gains | 337 |  | 263 |
Gross Unrealized Losses | (191) |  | (478) |
Fair Value | 6,875 |  | 8,810 |
Other-Than-Temporary Impairments | (47) | [1] | (139) | [1]
Other Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 624 |  | 1,060 |
Gross Unrealized Gains |  |  | 1 |
Gross Unrealized Losses |  |  | (19) |
Fair Value | 624 |  | 1,042 |
Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 5,644 |  | 7,492 |
Gross Unrealized Gains | 326 |  | 262 |
Gross Unrealized Losses | (161) |  | (418) |
Fair Value | 5,809 |  | 7,336 |
Other-Than-Temporary Impairments | (47) | [1] | (139) | [1]
Fixed-Maturity Investments [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 446 |  |  |
Fair Value | 427 |  |  |
Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 1,221 |  |  |
Fair Value | 1,246 |  |  |
Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 99 |  |  |
Fair Value | 87 |  |  |
Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 360 |  |  |
Fair Value | 275 |  |  |
Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 133 |  |  |
Fair Value | 123 |  |  |
Corporate Obligations [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 177 |  | 2 |
Gross Unrealized Gains | 7 |  |  |
Gross Unrealized Losses | (7) |  |  |
Fair Value | 177 |  | 2 |
Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 99 |  | 119 |
Gross Unrealized Losses | (12) |  | (26) |
Fair Value | 87 |  | 93 |
Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 108 |  | 112 |
Gross Unrealized Losses | (11) |  | (15) |
Fair Value | 97 |  | 97 |
Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 25 |  | 41 |
Gross Unrealized Gains | 1 |  |  |
Fair Value | 26 |  | 41 |
State And Municipal Bonds [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 37 |  |  |
Gross Unrealized Gains | 3 |  |  |
Fair Value | 40 |  |  |
Perpetual Preferred Securities [Member] | Other Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 31 |  | 127 |
Gross Unrealized Losses |  |  | (19) |
Fair Value | 31 |  | 108 |
Other Investment Securities [Member] | Other Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 10 |  | 22 |
Gross Unrealized Gains |  |  | 1 |
Fair Value | 10 |  | 23 |
Money Market Securities [Member] | Other Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 583 |  | 911 |
Fair Value | 583 |  | 911 |
Money Market Securities [Member] | Other Investments [Member] | Variable Interest Entity [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 15 |  | 199 |
Fair Value | 15 |  | 199 |
Taxable Bonds [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 4,758 |  | 6,370 |
Gross Unrealized Gains | 266 |  | 221 |
Gross Unrealized Losses | (161) |  | (416) |
Fair Value | 4,863 |  | 6,175 |
Other-Than-Temporary Impairments | (47) | [1] | (139) | [1]
Taxable Bonds [Member] | U.S. Treasury And Government Agency [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 896 |  | 1,091 |
Gross Unrealized Gains | 44 |  | 39 |
Gross Unrealized Losses | (1) |  |  |
Fair Value | 939 |  | 1,130 |
Taxable Bonds [Member] | Foreign Governments [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 318 |  | 326 |
Gross Unrealized Gains | 22 |  | 23 |
Fair Value | 340 |  | 349 |
Taxable Bonds [Member] | Corporate Obligations [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 1,068 |  | 1,698 |
Gross Unrealized Gains | 59 |  | 43 |
Gross Unrealized Losses | (21) |  | (106) |
Fair Value | 1,106 |  | 1,635 |
Other-Than-Temporary Impairments | 3 | [1] | (2) | [1]
Taxable Bonds [Member] | Residential Mortgage-Backed Agency [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 988 |  | 1,198 |
Gross Unrealized Gains | 48 |  | 47 |
Fair Value | 1,036 |  | 1,245 |
Taxable Bonds [Member] | Residential Mortgage-Backed Non-Agency [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 187 |  | 325 |
Gross Unrealized Gains | 16 |  | 31 |
Gross Unrealized Losses | (36) |  | (83) |
Fair Value | 167 |  | 273 |
Other-Than-Temporary Impairments | (24) | [1] | (57) | [1]
Taxable Bonds [Member] | Commercial Mortgage-Backed [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 46 |  | 58 |
Gross Unrealized Gains | 1 |  | 1 |
Gross Unrealized Losses | (4) |  | (10) |
Fair Value | 43 |  | 49 |
Taxable Bonds [Member] | Collateralized Debt Obligations [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 165 |  | 251 |
Gross Unrealized Losses | (74) |  | (118) |
Fair Value | 91 |  | 133 |
Other-Than-Temporary Impairments | (26) | [1] | (43) | [1]
Taxable Bonds [Member] | Other Asset-Backed [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 195 |  | 520 |
Gross Unrealized Gains | 3 |  | 2 |
Gross Unrealized Losses | (14) |  | (82) |
Fair Value | 184 |  | 440 |
Other-Than-Temporary Impairments |  |  | (37) | [1]
Taxable Bonds [Member] | State And Municipal Bonds [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 895 |  | 903 |
Gross Unrealized Gains | 73 |  | 35 |
Gross Unrealized Losses | (11) |  | (17) |
Fair Value | 957 |  | 921 |
Tax-Exempt Bonds [Member] | State And Municipal Bonds [Member] | Fixed-Maturity Investments [Member] |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Amortized Cost | 886 |  | 1,122 |
Gross Unrealized Gains | 60 |  | 41 |
Gross Unrealized Losses |  |  | (2) |
Fair Value | $ 946 |  | $ 1,161 |
[1] | Represents unrealized gains or losses on other than temporarily impaired securities recognized in accumulated other comprehensive income (loss), which includes the non-credit component of impairments, as well as all subsequent changes in fair value of such impaired securities.

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- Definition Cumulative other-than-temporary Impairment Of Securities Recognized in AOCI Since Adoption of Accounting Standard + References No definition available. + Details
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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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 7 -Footnote 2 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale. + References 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=7534914&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 + Details
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- Definition This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27161-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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