| **Investments in and advances to non-consolidated affiliates (Tables) (NC2 Global LLC [Member])** | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| NC2 Global LLC [Member]                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| **Schedule of Equity Method Investments [Line Items]**                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Summarized financial information for NC2 Global, LLC                                              | Presented below is summarized financial information representing 100% of NC2, which was considered a significant non-consolidated affiliate during the three and six months ended April 30, 2011, prior to the increase of our equity interest in September 2011. Balance sheet information for NC2 was insignificant to our Consolidated Balance Sheet as of April 30, 2011. (in millions)Three Months Ended April 30, 2011 Six Months Ended April 30, 2011Net revenue$30 $79Net expenses46 113Loss before tax expense(16) (34)Net loss(16) (34) |

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| - Definition
Tabular disclosure of equity method investments in common stock. The disclosure may include: (a) the name of each investee or group of investments for which combined disclosure is appropriate, (2) the percentage ownership of common stock, (3) the difference, if any, between the carrying amount of an investment and the value of the underlying equity in the net assets and the accounting treatment of difference, if any, and (4) the aggregate value of each identified investment based on its quoted market price, if available.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 20 -Subparagraph a, b -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 323 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571
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