Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
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Amount of liability recognized arising from contingent consideration in a business combination.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

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Fair value of financial and nonfinancial obligations.

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Fair Value Measurements (Details) - USD ($)	3 Months Ended		6 Months Ended
Fair Value Measurements (Details) - USD ($)	Jul. 04, 2020	Jun. 29, 2019	Jul. 04, 2020	Jun. 29, 2019	Dec. 31, 2019
Assets:
Available for sale securities	$ 448,231,000		$ 448,231,000		$ 518,502,000
Liabilities, Fair Value Disclosure [Abstract]
Transfers between fair value levels	0	$ 0	0	$ 0
U.S. government agencies
Assets:
Available for sale securities	24,083,000		24,083,000		77,364,000
Corporate debt securities
Assets:
Available for sale securities	80,672,000		80,672,000		207,137,000
Fair Value, Recurring
Assets:
Money market funds	241,249,000		241,249,000		107,708,000
Total	346,004,000		346,004,000		392,209,000
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	1,889,000		1,889,000		1,889,000
Derivative liabilities					748,000
Total	1,889,000		1,889,000		2,637,000
Fair Value, Recurring \| U.S. government agencies
Assets:
Available for sale securities	24,083,000		24,083,000		77,364,000
Fair Value, Recurring \| Corporate debt securities
Assets:
Available for sale securities	80,672,000		80,672,000		207,137,000
Fair Value, Recurring \| Level 1
Assets:
Money market funds	241,249,000		241,249,000		107,708,000
Total	241,249,000		241,249,000		107,708,000
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0		0		0
Derivative liabilities					0
Total	0		0		0
Fair Value, Recurring \| Level 1 \| U.S. government agencies
Assets:
Available for sale securities	0		0		0
Fair Value, Recurring \| Level 1 \| Corporate debt securities
Assets:
Available for sale securities	0		0		0
Fair Value, Recurring \| Level 2
Assets:
Money market funds	0		0		0
Total	104,755,000		104,755,000		284,501,000
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	0		0		0
Derivative liabilities					748,000
Total	0		0		748,000
Fair Value, Recurring \| Level 2 \| U.S. government agencies
Assets:
Available for sale securities	24,083,000		24,083,000		77,364,000
Fair Value, Recurring \| Level 2 \| Corporate debt securities
Assets:
Available for sale securities	80,672,000		80,672,000		207,137,000
Fair Value, Recurring \| Level 3
Assets:
Money market funds	0		0		0
Total	0		0		0
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration	1,889,000		1,889,000		1,889,000
Derivative liabilities					0
Total	1,889,000		1,889,000		1,889,000
Fair Value, Recurring \| Level 3 \| U.S. government agencies
Assets:
Available for sale securities	0		0		0
Fair Value, Recurring \| Level 3 \| Corporate debt securities
Assets:
Available for sale securities	$ 0		$ 0		$ 0