Segment and Geographic Information - Revenue and Long-Lived Assets by Geographical Areas (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales	$ 461,548	$ 482,342	$ 481,118	$ 477,565	$ 490,298	$ 464,107	$ 422,833	$ 346,073	$ 1,902,573	$ 1,723,311	$ 857,385
Total long-lived assets	358,681				322,797				358,681	322,797
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									309,495	297,699	204,963
Total long-lived assets	124,312				120,116				124,312	120,116
Foreign Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									1,593,078	1,425,612	652,422
Total long-lived assets	234,369				202,681				234,369	202,681
South Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									652,313	628,369	187,908
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									235,568	162,316	63,050
Europe, other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									171,936	162,162	55,351
Total long-lived assets	22,962				18,681				22,962	18,681
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									180,223	154,985	193,418
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									166,926	145,835	71,427
Total long-lived assets	168,755				159,483				168,755	159,483
Asia-Pacific, other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									124,733	107,713	36,364
Total long-lived assets	$ 42,652				$ 24,517				42,652	24,517
Rest of World
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales									$ 61,379	$ 64,232	$ 44,904