Costs and Estimated Earnings on Uncompleted Contracts - Costs and Estimated Earnings on Uncompleted Contracts (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Costs In Excess Of Billings On Uncompleted Contracts Or Programs [Abstract]
Costs incurred on uncompleted contracts	$ 187,190	$ 186,609
Estimated earnings	72,553	77,709
Contract Revenues	259,743	264,318
Less billings to date	(242,514)	(261,280)
Net bills receivable	17,229	3,038
Included in the accompanying condensed consolidated balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts	40,774	38,123
Billings in excess of costs and estimated earnings on uncompleted contracts	23,545	35,085
Net bills receivable	$ 17,229	$ 3,038