Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits
Balance at beginning of period	$ 4,096,000,000us-gaap_UnrecognizedTaxBenefits	$ 4,065,000,000us-gaap_UnrecognizedTaxBenefits	$ 4,045,000,000us-gaap_UnrecognizedTaxBenefits
Increases based on tax positions related to the current period	135,000,000	51,000,000	299,000,000
Increases based on tax positions related to prior periods	100,000,000	267,000,000	127,000,000
Decreases based on tax positions related to prior periods	(2,080,000,000)	(141,000,000)	(21,000,000)
Decreases related to settlements with taxing authorities	(19,000,000)	(146,000,000)	(260,000,000)
Decreases related to a lapse of applicable statute of limitations	(4,000,000)	0	(125,000,000)
Balance at end of period	2,228,000,000us-gaap_UnrecognizedTaxBenefits	4,096,000,000us-gaap_UnrecognizedTaxBenefits	4,065,000,000us-gaap_UnrecognizedTaxBenefits
Amount of unrecognized tax benefits, amount if recognized, would favorably affect the effective tax rate in future periods	1,000,000,000	1,400,000,000	1,600,000,000
Recognized interest expense (benefit) (net of federal and state income tax benefits)	(35,000,000)	50,000,000	(10,000,000)
Interest expense accrued	258,000,000	293,000,000	243,000,000
Gross unrecognized tax benefits	$ 2,000,000,000

The net amount of nonoperating interest income (expense).

No definition available.

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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

+ References

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-Publisher FASB

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of interest expense accrued for an underpayment of income taxes.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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