Income Taxes (Reconciliation of the tax provision at the U.S. Federal Statutory Rate) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Income Taxes
Tax provision at the U.S. federal statutory rate, amount	$ 2,584	$ 2,033	$ 1,618
State income taxes, net of federal benefit, amount	129	66	106
Settlement of state exams, net of federal benefit, amount	(3)	(40)	(12)
Tax-exempt investment income, amount	(65)	(70)	(69)
Non-deductible compensation, amount	64	0	0
Other, net, amount	40	(3)	4
Total provision for income taxes, amount	$ 2,749	$ 1,986	$ 1,647
Tax provision at the U.S. federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit, rate	1.70%	1.10%	2.20%
Settlement of state exams, net of federal benefit, rate	0.00%	(0.70%)	(0.20%)
Tax-exempt investment income, rate	(0.90%)	(1.20%)	(1.50%)
Non-Deductible Compensation, rate	0.90%	0.00%	0.00%
Other, net, rate	0.50%	0.00%	0.10%
Effective income tax rate	37.20%	34.20%	35.60%

Income Taxes [Abstract]

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- Definition

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 2
-Article 4

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- Definition

The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate shall be the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

+ Details

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- Definition

The sum of the differences between the effective income tax rate and domestic federal statutory income tax rate attributable to all nondeductible expenses under enacted tax laws.

+ Details

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense (benefit), net of the federal tax benefit (expense) thereon, recorded during the period.

+ Details

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to income that is exempt from income taxes under enacted tax laws.

+ Details

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to state and local income tax settlements during the period.

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- Definition

The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 45
-Subparagraph a, b

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The amount of income tax expense (benefit) for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

+ References

+ Details

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The sum of the differences between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible expenses under enacted tax laws, or differences in the methodologies used to determine expense amounts for financial statements prepared in accordance with generally accepted accounting principles and enacted tax laws.

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The portion of the difference, between total income tax expense (benefit) as reported in the Income Statement for the year/accounting period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to all other items not otherwise listed in the existing taxonomy.

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- Definition

The portion of the difference, between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense (benefit).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 1
-Article 4

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to income that is exempt from income taxes under enacted tax laws.

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to state and local income tax settlements for the period.

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