| **EQUITY INVESTMENT INCOME, NET**            | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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| **EQUITY INVESTMENT INCOME, NET [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| EQUITY INVESTMENT INCOME, NET [Text Block]   | 10.EQUITY INVESTMENT INCOME, NET Equity investment income includes investment income from Triton of $3.8 million and $11.2 million for the three and nine months ended September 30, 2011, respectively, and $1.5 million and $4.7 million, respectively, for the same periods in 2010.  Nicor received cash distributions from equity investees for the three and nine months ended September 30, 2011 of $4.3 million and $12.5 million, respectively, and $6.1 million and $14.0 million, respectively, for the same periods in 2010. |

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| - Definition
EQUITY INVESTMENT INCOME, NET
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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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