Revenues (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Apr. 01, 2018	Jul. 01, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings decrease	$ 45,737		$ 35,664
Decrease in costs in excess of billings	(77,008)		(82,358)
Increase in billings in excess of cost	$ 13,163		$ 14,667
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	$ 15,872
Billings in Excess of Cost
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously included in prior period obligation	7,601
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	(2,638)	$ 2,752
Decrease in costs in excess of billings	(1,330)	1,371
Increase in billings in excess of cost	$ (457)	455
Accounts receivable, net of allowance for doubtful accounts		10,385
Costs/estimated earnings in excess of billings on uncompleted contracts		5,350
Billings in excess of costs/estimated earnings on uncompleted contracts		1,504
Deferred revenue, current and long-term		1,358
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