The carrying amounts of the Corporation’s financial instru- ments and commodity contracts, including those used in the Corporation’s non-trading and trading activities, gener- ally approximate their fair values at December 31, 2003 and 2002, except as follows: The Corporation is subject to contingent liabilities with respect to existing or potential claims, lawsuits and other proceedings. The Corporation considers these routine and incidental to its business and not material to its financial position or results of operations. The Corporation accrues liabilities when the future costs are probable and reasonably estimable. Financial information by major geographic area for each of the three years ended December 31, 2003 follows: Credit Risks: The Corporation’s financial instruments expose it to credit risks and may at times be concentrated with certain counterparties or groups of counterparties. The credit worthiness of counterparties is subject to continuing review and full performance is anticipated. The Corporation reduces its risk related to certain counterparties by using master netting agreements and requiring collateral, generally cash. In its trading activities the Corporation has net receivables of $351 million at December 31, 2003, which are concentrated with counterparties as follows: domestic and foreign trading companies—25%, gas and power companies—25%, banks and major financial institutions—22%, government entities— 15% and integrated energy companies—7%. In the normal course of business, the Corporation provides guarantees principally for investees of the Corporation. These guarantees are contingent commitments that ensure performance for repayment of borrowings and other arrangements. The maximum potential amount of future payments that the Corporation could be required to make under its guarantees at December 31, 2003 is $99 million ($358 million at December 31, 2002). This amount includes the Corporation’s guarantee of $40 million of the senior debt obligation of HOVENSA (see note 7). The remainder relates generally to a loan guarantee of a natural gas pipeline in which the Corporation owns a 5% interest. The amount of this guarantee declines over its term. The Corporation has two operating segments that comprise the structure used by senior management to make key operating decisions and assess performance. These are (1) exploration and production and (2) refining and marketing. Operating segments have not been aggregated. Exploration and production operations include the exploration for and the production, purchase, transportation and sale of crude oil and natural gas. Refining and marketing operations include the manufacture, purchase, transportation, trading and marketing of petroleum and other energy products. 18. GUARANTEES AND CONTINGENCIES 19. SEGMENT INFORMATION 2003 2002 Balance Balance Millions of dollars,  Sheet Fair Sheet Fair asset (liability) Amount Value Amount Value Fixed-rate notes  receivable $ 363 $ 355 $ 424 $ 364 Fixed-rate debt  (3,935) (4,434) (4,984) (5,561) United Africa, Asia Consoli- Millions of dollars States Europe andother dated 2003 Operating revenues $12,019 $1,694 $ 598 $14,311 Property, plant and  equipment (net) 1,705 2,538 3,735 7,978 2002 Operating revenues $ 8,684 $2,185 $ 682 $11,551 Property, plant and  equipment (net) 1,770 2,327 2,935 7,032 2001 Operating revenues $ 9,663 $3,081 $ 308 $13,052 Property, plant and  equipment (net) 2,469 2,322 3,374 8,165 55