4.	Costs and Estimated Earnings on Uncompleted Contracts

Our contracts have various lengths to completion ranging from a few days to several months. We anticipate that a majority of our current contracts will be completed within the next twelve months. A significant amount of our revenue within the Energy Solutions and Industrial Solutions segments is recognized over a period of time as we perform under the contract because control of the work in process transfers continuously to the customer. The assets and liabilities recognized in association with these contracts are as follows:

(Table only in thousands)	September 30, 2018			December 31, 2017
Costs incurred on uncompleted contracts	$	164,400		$	169,665
Estimated earnings		60,561			61,556
Total costs and estimated earnings on uncompleted contracts, gross		224,961			231,221
Less billings to date		(223,575	)		(217,743	)
Total costs and estimated earnings on uncompleted contracts, net	$	1,386		$	13,478
Included in the accompanying condensed consolidated balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts	$	29,991		$	33,947
Billings in excess of costs and estimated earnings on uncompleted contracts		(28,605	)		(20,469	)
Total costs and estimated earnings on uncompleted contracts, net	$	1,386		$	13,478

Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined. Changes to job performance, job conditions, and estimated profitability may result in revisions to contract revenue and costs, and are recognized in the period in which the revisions are made. No provision for estimated losses on uncompleted contracts was required as of September 30, 2018 or December 31, 2017.