Fair Value Measurements Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 26, 2020		Sep. 26, 2020		Dec. 28, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 1,500		$ 1,500		$ 0
conversion of debt				1,500
Equity Securities, FV-NI, Unrealized Gain		4,900		5,500
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value		74,058		74,058
Equity Securities [Member]	[1]	52,106		52,106
Available-for-sale Securities		0	[2]	0	[2]	0
Convertible Debt, Fair Value Disclosures		0		0
Derivative Asset		0		0		0
Assets, Fair Value Disclosure		126,164		126,164		0
Derivative Liability		0		0		0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0		0		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value	[3]	0		0
Equity Securities [Member]	[3]	0		0
Available-for-sale Securities	[3]	6,524	[2]	6,524	[2]	17,032
Convertible Debt, Fair Value Disclosures	[3]	0		0
Derivative Asset	[3]	6,641		6,641		15,314
Assets, Fair Value Disclosure	[3]	13,165		13,165		32,346
Derivative Liability	[3]	5,927		5,927		758
Financial and Nonfinancial Liabilities, Fair Value Disclosure	[3]	5,927		5,927		758
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money Market Funds, at Carrying Value	[4]	0		0
Equity Securities [Member]		0		0
Available-for-sale Securities	[4]	0	[2]	0	[2]	0
Convertible Debt, Fair Value Disclosures	[4]	1,500		1,500
Derivative Asset	[4]	0		0		0
Assets, Fair Value Disclosure	[4]	1,500		1,500		0
Derivative Liability		0		0		0	[4]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		$ 0		$ 0		$ 0	[4]

[1] The related unrealized gain recorded in Other income, net was $5.5 million for the three months ended September 26, 2020. Marketable equity securities are included in short term investments on the consolidated balance sheet.

[2] As of September 26, 2020, the Company’s investments had maturity dates ranging from November 2020 to March 2021.

[3] Level 2 fair value estimates are based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

[4] Level 3 fair value estimates are based on inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. Unobservable inputs used in the models are significant to the fair values of the assets and liabilities.(3)The related unrealized gain recorded in Other income, net was $5.5 million for the three months ended September 26, 2020. Marketable equity securities are included in short term investments on the consolidated balance sheet.