Costs and Estimated Earnings in Excess of Billings (Details) - USD ($) $ in Thousands	Oct. 28, 2017	Jul. 29, 2017
Contractors [Abstract]
Costs incurred on contracts in progress	$ 351,361	$ 327,312
Estimated to date earnings	92,523	92,781
Total costs and estimated earnings	443,884	420,093
Less: billings to date	(43,966)	(40,091)
Total costs in excess of billings	399,918	380,002
Included in the accompanying condensed consolidated balance sheets under the captions:
Costs and estimated earnings in excess of billings	406,517	389,286
Billings in excess of costs and estimated earnings	(6,599)	(9,284)
Total costs in excess of billings	$ 399,918	$ 380,002