The percentage of pre-tax income on income before federal and foreign income tax.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Glossary Income Tax Expense (or Benefit)

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

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments.

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Federal and Foreign Income Tax - Reconciliation of Effective Income Tax Rate and Statutory Federal Corporate Tax Rate (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income before federal and foreign income tax									$ 2,861	$ 3,237	$ 1,996
Tax at statutory federal income tax rate									1,001	1,133	699
Tax exempt interest income									(212)	(222)	(233)
Other, net									(28)	(19)	(15)
Federal and foreign income tax	$ 204us-gaap_IncomeTaxExpenseBenefit	$ 224us-gaap_IncomeTaxExpenseBenefit	$ 179us-gaap_IncomeTaxExpenseBenefit	$ 154us-gaap_IncomeTaxExpenseBenefit	$ 217us-gaap_IncomeTaxExpenseBenefit	$ 198us-gaap_IncomeTaxExpenseBenefit	$ 217us-gaap_IncomeTaxExpenseBenefit	$ 260us-gaap_IncomeTaxExpenseBenefit	$ 761us-gaap_IncomeTaxExpenseBenefit	$ 892us-gaap_IncomeTaxExpenseBenefit	$ 451us-gaap_IncomeTaxExpenseBenefit
Income before federal and foreign income tax, percentage of Pre-Tax Income
Tax at statutory federal income tax rate, percentage of Pre-Tax Income									35.00%	35.00%	35.00%
Tax exempt interest income, percentage of Pre-Tax Income									(7.40%)	(6.80%)	(11.70%)
Other, net, percentage of Pre-Tax Income									(1.00%)	(0.60%)	(0.70%)
Federal and foreign income tax, percentage of Pre-Tax Income									26.60%	27.60%	22.60%