Investment in Unconsolidated Joint Venture - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2011
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Cash dividend received from joint venture	$ 25

Cash dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporations that are returns of capital. Excludes dividends or distributions from equity method investments classified as operating activities.

No definition available.

Name:	us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration