Note 3 - Merger with Nicor (Detail) - Estimated Fair Value of the Acquired Receivables (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Nicor accounts receivable at December 9, 2011	$ 400
Cash flows not expected to be collected	24
Fair value of acquired receivables	$ 376

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the contractual cash flows not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

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For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the fair value of the receivables acquired, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

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- Definition

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

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