Fair Value Measurements (Details) - USD ($) shares in Millions		3 Months Ended	12 Months Ended
	Aug. 09, 2018	Dec. 30, 2018	Dec. 30, 2018	Dec. 31, 2017	Jan. 01, 2017
Prepaid expenses and other current assets:
Derivative Asset		$ 729,000	$ 729,000	$ 2,579,000
Other long-term assets:
Marketable equity investments (Note 11)		36,225,000	36,225,000	0
Total assets		36,954,000	36,954,000	2,579,000
Accrued liabilities:
Derivative financial instruments (Note 13)		1,161,000	1,161,000	1,452,000
Other long-term liabilities:
Derivative financial instruments (Note 13)		152,000	152,000	1,174,000
Total liabilities		1,313,000	1,313,000	2,626,000
Debt Securities, Held-to-maturity [Abstract]
Bonds, carrying value		6,000,000	6,000,000	6,200,000
Other than temporary impairment loss		0
Unrealized loss on equity investments with readily determinable fair value			6,375,000	0	$ 0
Non-marketable equity investments accounted for under the measurement alternative method		8,810,000	8,810,000	35,840,000
Equity method investments		43,659,000	43,659,000	450,000,000
Fair Value, Inputs, Level 2
Prepaid expenses and other current assets:
Derivative financial instruments (Note 13)		729,000	729,000
Derivative Asset		729,000	729,000	2,579,000
Other long-term assets:
Marketable equity investments (Note 11)				0
Total assets		729,000	729,000	2,579,000
Accrued liabilities:
Derivative financial instruments (Note 13)		1,161,000	1,161,000	1,452,000
Other long-term liabilities:
Derivative financial instruments (Note 13)		152,000	152,000	1,174,000
Total liabilities		1,313,000	1,313,000	$ 2,626,000
Fair Value, Inputs, Level 1
Prepaid expenses and other current assets:
Derivative Asset		0	0
Other long-term assets:
Marketable equity investments (Note 11)		36,225,000	36,225,000
Total assets		36,225,000	36,225,000
Other long-term liabilities:
Total liabilities		$ 0	$ 0
Enphase shares
Debt Securities, Held-to-maturity [Abstract]
Shares issuable to the Company at closing of agreement	7.5