Rental Equipment Operating Leases (Details) (Rental equipment, USD $) In Millions, unless otherwise specified	6 Months Ended
Sep. 30, 2012
Rental equipment
Contingent liabilities and commitments:
Lease expiration year	2019
Guaranteed residual value	$ 124
Started leasing equipment date	1987

The estimate of the value of the leased asset at the end of the lease term.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 840

-SubTopic 30

-Section 30

-Paragraph 14

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

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