Revenues (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 29, 2018	Apr. 01, 2018	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings decrease	$ 22,842		$ 35,664
Decrease in costs in excess of billings	(50,826)		(52,696)
Increase in billings in excess of cost	$ 12,176		$ 12,547
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Demand services, duration of work completion period	1 day
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Demand services, duration of work completion period	30 days
Deferred Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously included in prior period obligation	$ 23,610
Billings in Excess of Cost
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously included in prior period obligation	5,490
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings decrease	2,436	$ 2,752
Decrease in costs in excess of billings	(1,137)	1,371
Increase in billings in excess of cost	$ 422	455
Accounts receivable, net of allowance for doubtful accounts		4,859
Costs/estimated earnings in excess of billings on uncompleted contracts		1,870
Billings in excess of costs/estimated earnings on uncompleted contracts		371
Deferred revenue, current and long-term		2,771
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606 | Deferred Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings decrease		$ 1,826