Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Effective income tax rate	29.60%	31.80%	33.30%
Income taxes paid, net	$ 727us-gaap_IncomeTaxesPaidNet	$ 880us-gaap_IncomeTaxesPaidNet	$ 1,100us-gaap_IncomeTaxesPaidNet
Section 199 manufacturing deductions, increase from prior year		21
Income Tax Reconciliation (Table Amounts) [Abstract]
Income tax expense at statutory rate	1,028	1,002	1,038
Settlements with taxing authorities	(51)	0	0
Manufacturing deduction	(48)	(63)	(42)
Research tax credit	(43)	(37)	0
Other, net	(18)	9	(9)
Total federal and foreign income taxes	$ 868us-gaap_IncomeTaxExpenseBenefit	$ 911us-gaap_IncomeTaxExpenseBenefit	$ 987us-gaap_IncomeTaxExpenseBenefit

Effective Tax Rate Reconciliation, Deduction, Qualified Production Activity, Increase from Prior Year, Amount

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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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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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

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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 income tax settlements. Including, but not limited to, domestic tax settlement, foreign tax settlement, state and local tax settlement, and other tax settlements.

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