Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Sep. 29, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accrued Liabilities, Current	$ 130,083	$ 126,500		$ 130,083
Liabilities, Current	196,728	176,329		196,728
Deferred income taxes	8,580	7,577		8,580
Retained earnings	246,723	209,381		246,723
Stockholders' Equity Attributable to Parent	494,748	457,106		494,748
Revenues	241,530		$ 200,507	487,933	$ 407,323
Cost of Revenue	192,114		165,953	387,041	330,803
Gross Profit	49,416		34,554	100,892	76,520
Selling, General and Administrative Expense	30,035		26,153	59,248	52,458
Operating Income (Loss)	19,381		8,401	41,644	24,062
Income before income taxes	19,517		8,499	43,653	24,150
Income Tax Expense (Benefit)	(3,941)		(2,317)	(8,386)	(6,215)
Net income	15,576		6,182	35,267	17,935
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accrued Liabilities, Current	132,090			132,090
Liabilities, Current	198,735			198,735
Deferred income taxes	8,031			8,031
Retained earnings	245,265			245,265
Stockholders' Equity Attributable to Parent	493,290			493,290
Revenues	232,370			465,104
Cost of Revenue	183,423			365,961
Gross Profit	48,947			99,143
Selling, General and Administrative Expense	29,899			58,804
Operating Income (Loss)	19,048			40,339
Income before income taxes	19,184			42,348
Income Tax Expense (Benefit)	(3,865)			(8,085)
Net income	15,319			34,263
Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results	(469)			(1,749)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(257)			(1,004)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	6,200		$ 5,000	12,800	$ 10,100
Revenue from Contract with Customer [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(9,160)			(22,829)
Cost of Sales [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(8,691)			(21,080)
Selling, General and Administrative Expenses [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(136)			(444)
Operating Income (Loss) [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(333)			(1,305)
Other Expense [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	$ 76			301
Accrued Liabilities [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		$ 600		2,007
Other Current Liabilities [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income				2,007
Deferred Tax Asset [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income				(549)
Retained earnings
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income				(1,458)
Stockholders' Equity, Total [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income				$ (1,458)