SEGMENT INFORMATION (Operating information by segment) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Jan. 02, 2016	Oct. 03, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 27, 2014	Oct. 01, 2016	Oct. 03, 2015	Sep. 27, 2014
Net revenue:
Net revenue	$ 145,844	$ 216,414	$ 156,400	$ 108,534	$ 119,172	$ 164,634	$ 145,227	$ 107,438	$ 627,192	$ 536,471	$ 568,569
Cost of sales :
Cost of sales									340,463	277,379	295,015
Gross profit :
Gross profit	66,621	100,040	69,647	50,421	58,217	77,571	68,570	54,734	286,729	259,092	273,554
Operating expenses:
Operating expenses									234,190	221,841	196,570
Income from operations:
Income from operations	$ 3,913	$ 38,622	$ 11,709	$ (1,705)	$ 1,648	$ 16,086	$ 9,791	$ 9,726	52,539	37,251	76,984
Equipment [Member]
Net revenue:
Net revenue									562,463	472,002	503,049
Income from operations:
Income from operations									35,750	21,618	59,769
Expendable Tools [Member]
Net revenue:
Net revenue									64,729	64,469	65,520
Income from operations:
Income from operations									$ 16,789	$ 15,633	$ 17,215