DERIVATIVE INSTRUMENTS (Policies)	9 Months Ended
Sep. 30, 2011
DERIVATIVE INSTRUMENTS [Abstract]
Cash Flow Hedge Effectiveness Policy	Changes in the fair value of derivatives designated as a cash flow hedge are recognized in other comprehensive income until the hedged transaction is recognized in the Condensed Consolidated Statements of Income. Cash flow hedges used by the company’s other energy ventures, to hedge utility-bill management products, are eventually recognized within operating revenues. Cash flow hedges used by Nicor Gas, to hedge purchases of natural gas for company use, are eventually recorded within operating and maintenance expense. Cash flow hedges used by Nicor, to hedge the interest payments attributable to long-term fixed-rate debt, will eventually be recorded within interest expense.
Derivative Not Designated as Hedges Policy	Non-designated derivatives used by the company’s other energy ventures, to hedge energy trading activities and utility-bill management products, are recorded in operating revenues. Non-designated derivatives used by Nicor Gas, to hedge purchases of natural gas for company use, are recorded within operating and maintenance expense. Nicor Gas’ derivatives used to hedge the purchase of natural gas for its customers are also not designated as hedging instruments. Gains or losses on these derivatives are not recognized in pretax earnings, but are deferred as regulatory assets or liabilities until the related revenue is recognized.

DERIVATIVE INSTRUMENTS (Policies)

9 Months Ended

Sep. 30, 2011

Changes in the fair value of derivatives designated as a cash flow hedge are recognized in other comprehensive income until the hedged transaction is recognized in the Condensed Consolidated Statements of Income. Cash flow hedges used by the company’s other energy ventures, to hedge utility-bill management products, are eventually recognized within operating revenues. Cash flow hedges used by Nicor Gas, to hedge purchases of natural gas for company use, are eventually recorded within operating and maintenance expense. Cash flow hedges used by Nicor, to hedge the interest payments attributable to long-term fixed-rate debt, will eventually be recorded within interest expense.

Derivative Not Designated as Hedges Policy

Non-designated derivatives used by the company’s other energy ventures, to hedge energy trading activities and utility-bill management products, are recorded in operating revenues. Non-designated derivatives used by Nicor Gas, to hedge purchases of natural gas for company use, are recorded within operating and maintenance expense.

Nicor Gas’ derivatives used to hedge the purchase of natural gas for its customers are also not designated as hedging instruments. Gains or losses on these derivatives are not recognized in pretax earnings, but are deferred as regulatory assets or liabilities until the related revenue is recognized.