Accounts receivable and allowance for doubtful accounts

6 Months Ended

Jun. 30, 2011

Accounts receivable and allowance for doubtful accounts [Abstract]

Accounts receivable and allowance for doubtful accounts

3. Accounts receivable and allowance for doubtful accounts

Accounts receivable consists primarily of trade receivables from the sale of goods and services which are recorded at the invoiced amount net of allowance for doubtful accounts, and costs and estimated earnings in excess of billings on uncompleted contracts. The total balance of receivables past due 90 days or more was $41.4 million and $21.6 million as of June 30, 2011 and December 31, 2010, respectively.

The allowance for doubtful accounts is determined through a review of past due balances and other specific account data. Account balances are written off when management determines the amounts to be uncollectible. The Company's allowance for doubtful accounts as of June 30, 2011 and 2010, and December 31, 2010, was $14.2 million, $14.9 million and $15.3 million, respectively.