Cost Method Investment and Collaborative Arrangement (Details) - USD ($)	3 Months Ended				6 Months Ended			12 Months Ended		42 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jul. 01, 2017	Oct. 01, 2016	Dec. 31, 2018	Jun. 30, 2018	Jul. 01, 2017	Dec. 28, 2019	Jan. 02, 2016	Jun. 30, 2018
Schedule of Investments [Line Items]
Investment made during fiscal year				$ 1,000,000					$ 5,000,000
Ownership interest percentage									22.70%
Gross investments amount				$ 6,000,000
Decrease of cost method investment										$ (3,700,000)
Beginning balance	$ 2,300,000					$ 2,300,000				2,300,000
Maximum loss exposure amount	4,700,000					4,700,000				4,700,000
Cost method investments, fair value	2,300,000					2,300,000				2,300,000
Prepaid royalties	2,400,000					2,400,000				2,400,000
Impairment of cost-method investment	0		$ 200,000			0	$ 493,000
Payments for royalties	900,000	$ 900,000
Forecast
Schedule of Investments [Line Items]
Payments for royalties					$ 1,750,000			$ 5,000,000
Prepaid Expenses and Other Current Assets
Schedule of Investments [Line Items]
Prepaid royalties	400,000					400,000				400,000
Other Long-term Assets
Schedule of Investments [Line Items]
Prepaid royalties	$ 2,000,000					$ 2,000,000				$ 2,000,000