Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2011	Dec. 31, 2011
Significant Accounting Policies [Abstract]
Revenue recognition, new accounting pronouncement	$ 15	$ 15

For arrangements that precede the adoption of the amending guidance, the amount of revenue that would have been recognized in the reporting period under the amended guidance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 65

-Paragraph 1

-Subparagraph c

-Topic 985

-SubTopic 605

-URI http://asc.fasb.org/extlink&oid=6751208&loc=SL6751214-165967

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

-Publisher FASB

-Name Accounting Standards Codification

-Section 65

-Paragraph 1

-Subparagraph (d)(1)

-Topic 605

-SubTopic 25

-URI http://asc.fasb.org/extlink&oid=6940631&loc=SL6749767-165964

Name:	us-gaap_RevenueRecognitionNewAccountingPronouncementMaterialEffectRevenueRecognizedUnderAmendedGuidance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration