Gas in storage. Nicor Gas’ inventory is carried at cost on a LIFO basis. Inventory decrements occurring during interim periods that are expected to be restored prior to year-end are charged to cost of gas at the estimated annual replacement cost, and the difference between this cost and the actual LIFO layer cost is recorded on the balance sheet as a temporary LIFO inventory liquidation. Interim inventory decrements not expected to be restored prior to year-end are charged to cost of gas at the actual LIFO cost of the layers liquidated. The inventory decrement as of June 30, 2011 is expected to be restored prior to year-end.

Nicor Enerchange’s inventory is carried at the lower of weighted-average cost or market (market is represented by the cash price per the close of business on the last trading day of the period). In the second quarter of 2011 and first quarter of 2010, Nicor Enerchange recorded a charge of $0.8 million and $5.0 million, respectively, resulting from lower of cost or market valuations.

Regulatory assets and liabilities. Nicor Gas is regulated by the ICC, which establishes the rules and regulations governing utility rates and services in Illinois. As a rate-regulated company, Nicor Gas is required to recognize the economic effects of rate regulation and, accordingly, has recorded regulatory assets and liabilities. Regulatory assets represent probable future revenue associated with certain costs that are expected to be recovered from customers through rate riders or base rates, upon approval by the ICC. Regulatory liabilities represent probable future reductions in revenues collected from ratepayers through a rate rider or base rates, or probable future expenditures. If Nicor Gas’ operations become no longer subject to rate regulation, a write-off of net regulatory liabilities would be required.

	June 30		December 31		June 30
	2011		2010		2010
Regulatory assets - current
Regulatory postretirement asset	$	21.1	$	21.1	$	20.6
Deferred gas costs		-		6.5		-
Bad debt rider		-		-		18.7
Other		10.5		7.4		7.2
Regulatory assets - noncurrent
Regulatory postretirement asset		185.6		193.3		187.6
Deferred gas costs		-		1.4		7.8
Deferred environmental costs		45.5		25.0		23.1
Unamortized losses on reacquired debt		12.6		13.1		13.7
Other		8.5		9.6		12.4
	$	283.8	$	277.4	$	291.1

Regulatory liabilities - current
Regulatory asset retirement liability	$	17.2	$	17.2	$	14.5
Accrued gas costs		1.3		-		15.5
Bad debt rider		26.6		16.4		-
Other		2.4		7.7		12.8
Regulatory liabilities - noncurrent
Regulatory asset retirement liability		866.9		843.9		825.7
Regulatory income tax liability		13.8		18.2		20.2
Bad debt rider		10.7		11.7		3.1
Other		1.2		.9		.8
	$	940.1	$	916.0	$	892.6

The ICC does not presently allow Nicor Gas the opportunity to earn a return on its regulatory postretirement asset. This regulatory postretirement asset is expected to be recovered from ratepayers over a period of approximately 9 to 12 years. The regulatory assets related to debt are not included in rate base, but are recovered over the term of the debt through the rate of return authorized by the ICC. Nicor Gas is allowed to recover and is required to pay, using short-term interest rates, the carrying costs related to temporary under or overcollections of natural gas costs, certain environmental costs and energy efficiency program costs charged to its customers. However, there is no interest associated with the under or overcollections of bad debt expense.

Revenue recognition. Nicor Gas accrues revenues for estimated deliveries to customers from the date of their last bill until the balance sheet date. Receivables include accrued unbilled revenues of $29.3 million, $144.8 million and $32.0 million at June 30, 2011, December 31, 2010 and June 30, 2010, respectively, related primarily to gas distribution operations.

Nicor Gas classifies revenue taxes billed to customers as operating revenues and related taxes incurred as operating expenses. Revenue taxes included in operating expense for the three and six months ended June 30, 2011 were $31.0 million and $104.7 million, respectively, and $23.5 million and $96.4 million, respectively, for the same periods in 2010.

Derivative instruments. Cash flows from derivative instruments are recognized in the Condensed Consolidated Statements of Cash Flows, and gains and losses are recognized in the Condensed Consolidated Statements of Income, in the same categories as the underlying transactions.

Cash flow hedge accounting may be elected only for highly effective hedges, based upon an assessment, performed at least quarterly, of the historical and probable future correlation of cash flows from the derivative instrument to changes in the expected future cash flows of the hedged item. To the extent cash flow hedge accounting is applied, the effective portion of any changes in the fair value of the derivative instruments is reported as a component of accumulated other comprehensive income. Ineffectiveness, if any, is immediately recognized in operating income. The amount in accumulated other comprehensive income is reclassified to earnings when the forecasted transaction is recognized in the Condensed Consolidated Statements of Income, even if the derivative instrument is sold, extinguished or terminated prior to the transaction occurring. If the forecasted transaction is no longer expected to occur, the amount in accumulated other comprehensive income is immediately reclassified to operating income.

Nicor Gas. Derivative instruments, such as futures contracts, options and swap agreements, are utilized primarily in the purchase of natural gas for customers. These derivative instruments are reflected at fair value and are not designated as hedges. Realized gains or losses on such instruments are included in the cost of gas delivered and are passed directly through to customers, subject to ICC review, and therefore have no direct impact on earnings. Unrealized changes in the fair value of these derivative instruments are deferred as regulatory assets or liabilities.

Nicor Gas enters into swap agreements to reduce the earnings volatility of certain forecasted operating costs arising from fluctuations in natural gas prices, such as the purchase of natural gas for use in company operations. These derivative instruments are carried at fair value. To the extent hedge accounting is not elected, changes in such fair values are immediately recorded in the current period as operating and maintenance expense.

Nicor Enerchange. Derivative instruments, such as futures contracts, options, forward contracts, swap agreements and other energy-related contracts are held by Nicor’s wholesale natural gas marketing business, Nicor Enerchange, for trading purposes. Certain of these derivative instruments are used to economically hedge price risk associated with inventories of natural gas, fixed-price purchase and sale agreements and other future natural gas commitments. Nicor Enerchange records such derivative instruments at fair value and generally does not elect hedge accounting. As a result, changes in derivative fair values may have a material impact on Nicor’s financial statements.

Other derivative instruments are used by Nicor Enerchange to hedge price risks related to the activities of affiliates. Derivatives are held related to certain utility-bill management products sold to retail customers. These derivative instruments are carried at fair value and cash flow hedge accounting may or may not be elected. Other derivative instruments are held for the purpose of hedging the commodity price risk associated with the forecasted purchase of base gas that will be injected as part of the development of the natural gas storage facility by Central Valley. Such derivative instruments are carried at fair value and cash flow hedge accounting has been elected on a consolidated basis. The base gas is a component of the storage facility’s construction costs. Therefore, amounts recorded in accumulated other comprehensive income related to these derivative instruments will not be reclassified to earnings until the storage facility is retired and the base gas is sold.

Nicor. Forward-starting interest rate swaps are utilized to hedge the interest payments associated with long-term debt. These derivative instruments are carried at fair value and cash flow hedge accounting is elected. The effective portion of any changes in the fair value of the derivatives is deferred in accumulated other comprehensive income. Upon settlement, the deferred amount is amortized to interest expense over the life of the debt.

Credit risk and concentrations. Nicor’s major subsidiaries have diversified customer bases and the company believes that it maintains prudent credit policies which mitigate customer receivable, supplier performance and derivative counterparty credit risk. The company is exposed to credit risk in the event a customer or supplier defaults on a contract to pay for or deliver product at agreed-upon terms and conditions, or a counterparty to a derivative instrument defaults on a settlement or otherwise fails to perform under contractual terms. To manage this risk, the company has established procedures to determine and monitor the creditworthiness of counterparties, to seek guarantees or collateral back-up in the form of cash or letters of credit, to acquire credit insurance in certain instances, and to limit its exposure to any one counterparty. Nicor also, in some instances, enters into netting arrangements to mitigate counterparty credit risk. Fair value measurements consider credit risk. For assets and liabilities not carried at fair value, credit losses are accrued when probable and reasonably estimable.

On February 2, 2010, the ICC approved a bad debt rider that was filed in 2009 by Nicor Gas. The bad debt rider provides for the recovery from (or refund to) customers of the difference between Nicor Gas’ actual bad debt experience on an annual basis and the benchmark bad debt expense included in its rates for the respective year.