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Quarterly Results (Unaudited) (Details 2) (Sell of Discoverer 534 and Jim Cunningham, USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2012
Sell of Discoverer 534 and Jim Cunningham
Quarterly results
Gain (loss) on the sale of assets	$ 51

X

- Definition

Amount of gain (loss) on sale or disposal of an equity method investment.

+ References

No definition available.

+ Details

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

X

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration