Income Tax Provision (Deferred Tax Assets and Liabilities) (Details) (USD $)	Jun. 30, 2013	Mar. 31, 2013
Deferred Tax Assets Liabilities, Net [Line Items]
Net deferred income tax liability	$ 6,290,000,000	$ 6,236,000,000
Tax Assets
Deferred tax assets	1,200,000,000	1,200,000,000
Net deferred income tax liability	$ 6,290,000,000	$ 6,236,000,000

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 43, 289

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Deferred Tax Asset

-URI http://asc.fasb.org/extlink&oid=6510090

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant