Analysis of Cost or Amortized Cost, Gross Unrealized Gains and Losses and Fair Value for Investments (Detail) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	$ 10,233	$ 10,174
Gross Unrealized Gains	1,485	1,299
Gross Unrealized Losses	30	49
Fair Value	11,688	11,424
OTTI in AOCI
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	8,118	7,888
Gross Unrealized Gains	607	515
Gross Unrealized Losses	8	20
Fair Value	8,717	8,383
OTTI in AOCI
Debt Securities \| US States and Political Subdivisions Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3,077	3,043
Gross Unrealized Gains	157	110
Gross Unrealized Losses	3	10
Fair Value	3,231	3,143
OTTI in AOCI
Debt Securities \| Convertibles and Bonds with Warrants Attached
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	73	69
Fair Value	73	69
OTTI in AOCI
Debt Securities \| US Government Agencies Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	5	4
Gross Unrealized Gains	1	1
Fair Value	6	5
OTTI in AOCI
Debt Securities \| US Government-sponsored Enterprises Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	163	201
Gross Unrealized Losses	1	1
Fair Value	162	200
OTTI in AOCI
Debt Securities \| Foreign Government
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	3	3
Fair Value	3	3
OTTI in AOCI
Debt Securities \| Corporate Bond Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	4,797	4,568
Gross Unrealized Gains	449	404
Gross Unrealized Losses	4	9
Fair Value	5,242	4,963
OTTI in AOCI
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,115	2,286
Gross Unrealized Gains	878	784
Gross Unrealized Losses	22	29
Fair Value	2,971	3,041
OTTI in AOCI
Equity Securities \| Common Stock
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	2,040	2,211
Gross Unrealized Gains	845	757
Gross Unrealized Losses	21	28
Fair Value	2,864	2,940
OTTI in AOCI
Equity Securities \| Preferred Stock
Schedule of Available-for-sale Securities [Line Items]
Cost or Amortized Cost	75	75
Gross Unrealized Gains	33	27
Gross Unrealized Losses	1	1
Fair Value	107	101
OTTI in AOCI

For an unclassified balance sheet, this item represents investments in debt and equity securities which are 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 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

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 FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15E
-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 4: 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 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15D
-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 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13
-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 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15C
-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 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 14
-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 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 16
-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 10: 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=6379932&loc=d3e22054-111558

+ Details

- 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+ Details

- 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+ Details