Income Tax Provision (Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014	Mar. 31, 2014
Deferred Tax Assets Liabilities, Net [Line Items]
Net deferred income tax liability	$ 7,340,000,000us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 6,747,000,000us-gaap_DeferredTaxAssetsLiabilitiesNet
Tax Assets
Deferred tax assets	2,000,000,000us-gaap_DeferredTaxAssetsGross	1,300,000,000us-gaap_DeferredTaxAssetsGross
Net deferred income tax liability	$ 7,340,000,000us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 6,747,000,000us-gaap_DeferredTaxAssetsLiabilitiesNet

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 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 2: 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

Name:	us-gaap_DeferredTaxAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant