Restructuring (narrative) (detail) - USD ($)	3 Months Ended
	Jul. 02, 2016	Jun. 27, 2015
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	$ 1,185,000	$ (81,000)
NorthwestPlant2 [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	1,185,000	10,302,000
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	127,000	(81,000)
Employee Severance [Member] | NorthwestPlant2 [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	127,000	162,000
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	1,064,000
Other Restructuring [Member] | NorthwestPlant2 [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	33,000	5,075,000
Long Lived Asset Charges [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	(6,000)
Long Lived Asset Charges [Member] | NorthwestPlant2 [Member]
Restructuring Cost and Reserve [Line Items]
Plant Restructuring	$ 1,025,000	$ 5,065,000