11. Billed and unbilled receivables

        Changes in the reserves against current billed, billable and unbilled accounts receivable were as follows (in thousands):

        In evaluating the net realizable value of accounts receivable, we consider such factors as current economic trends, customer credit-worthiness, and changes in the customer payment terms and collection trends. Changes in the assumptions used in analyzing a specific account receivable may result in a reserve being recognized in the period in which the change occurs.

        At September 30, 2015 and 2014, $12.1 million and $8.8 million of our unbilled receivables related to amounts pursuant to contractual retainage provisions. We anticipate that the majority of the fiscal 2015 balance will be collected during the 2016 fiscal year.