Contingencies (Details) (A T A Airlines [Member], USD $) In Millions	12 Months Ended
May 31, 2011
A T A Airlines [Member]
Loss Contingency [Line Items]
Loss Contingency Awarded Damages	$ 66
Loss Contingency Awarded Interest	5
Loss Contingency Reserved	$ 66

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant