Financial Information for Reportable Segments (Parenthetical) (Detail) (Unallocated, USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2012
Unallocated
Segment Reporting Information [Line Items]
Pretax gain related to confidential resolution of a vendor dispute	$ 70

This element represents the gross amount awarded, to be received by, or to be remitted to the entity in settlement of litigation occurring during the period.

No definition available.

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