Income Taxes (Unaudited) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2016
Income Tax Contingency [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	$ (75)
Income Tax Expense (Benefit)	220us-gaap_IncomeTaxExpenseBenefit	207us-gaap_IncomeTaxExpenseBenefit
Effective income tax rate	31.30%	26.30%
Tax Adjustments, Settlements, and Unusual Provisions	51
Maximum \| Scenario, Forecast [Member]
Income Tax Contingency [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions			$ (40)

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Subparagraph (SX 210.4-08.(h))

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-Glossary Income Tax Expense (or Benefit)

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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.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

+ References

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