Income Tax Provision (Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2012	Mar. 31, 2012
Deferred Tax Assets Liabilities, Net [Line Items]
Net deferred income tax liability	$ 6,060,000,000	$ 5,412,000,000
Deferred Tax Assets
Deferred tax assets	1,300,000,000	1,700,000,000
Net deferred income tax liability	$ 6,060,000,000	$ 5,412,000,000

The sum of the tax effects as of the balance sheet date of the amounts of all future tax deductions arising from temporary differences between tax basis and generally accepted accounting principles basis recognition of assets, liabilities, revenues and expenses, which can only be deducted for tax purposes when permitted under enacted tax laws ( before the valuation allowance, if any, to reduce such sum amount to net realizable value). Includes any tax benefit realized in deferred tax assets for significant impacts of tax planning strategies.

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For entities that net deferred tax assets and tax liabilities, represents the unclassified net amount of deferred tax assets and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods.

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