Accounts receivable
Accounts receivable include amounts invoiced to customers, amounts where revenue recognition criteria have been fulfilled but the customers have not yet been invoiced, and amounts where the contractual rights to the cash flows have been confirmed but the customers have not yet been invoiced. Billed accounts receivable are carried at the amount invoiced to customers less allowances for doubtful accounts. Allowances for doubtful accounts are based on a periodic review of all outstanding amounts, including an analysis of historical bad debt, customer concentrations, customer creditworthiness, past due amounts, current economic trends and changes in customer payment terms. Impairment charges on receivables identified as uncollectible are included in other operating expenses in the consolidated income statement.