Fair Value Measurements - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Mar. 29, 2020	Dec. 29, 2019
Debt Securities, Available-for-sale [Abstract]
Available-for-sale Securities - Estimated Fair Value	$ 5,673	$ 4,368
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	15,530	17,305
Marketable securities	2,494	$ 1,982
Total cash, cash equivalents and current marketable securities, Carrying Amount	18,022
Total cash, cash equivalents and current marketable securities, Unrecognized Gain	5
Total cash, cash equivalents and current marketable securities, Unrecognized Loss	(3)
Total cash, cash equivalents and current marketable securities, Estimated Fair Value	18,024
Held-to-maturity Securities
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	12,351
Held-to-maturity Securities, Unrecognized Gain	1
Held-to-maturity Securities, Unrecognized Loss	(1)
Held-to-maturity Securities - Estimated Fair Value	12,351
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	11,255
Marketable securities	1,096
Held-to-maturity Securities \| Cash
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	2,499
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	2,499
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	2,499
Held-to-maturity Securities \| Non-U.S. sovereign securities(1)
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	90
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	90
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	90
Marketable securities	0
Held-to-maturity Securities \| U.S. reverse repurchase agreements
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	3,965
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	3,965
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	3,965
Marketable securities	0
Held-to-maturity Securities \| Other reverse repurchase agreements
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	473
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	473
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	473
Held-to-maturity Securities \| Corporate debt securities(1)
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	2,135
Held-to-maturity Securities, Unrecognized Gain	1
Held-to-maturity Securities, Unrecognized Loss	(1)
Held-to-maturity Securities - Estimated Fair Value	2,135
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	1,039
Marketable securities	1,096
Held-to-maturity Securities \| Money market funds
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	2,424
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	2,424
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	2,424
Held-to-maturity Securities \| Time deposits(1)
Debt Securities, Held-to-maturity [Abstract]
Held-to-maturity Securities - Carrying Amount	765
Held-to-maturity Securities, Unrecognized Gain	0
Held-to-maturity Securities, Unrecognized Loss	0
Held-to-maturity Securities - Estimated Fair Value	765
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	765
Available-for-sale Securities
Debt Securities, Available-for-sale [Abstract]
Available-for-sale Securities - Carrying Amount	5,671
Available-for-sale Securities, Unrecognized Gain	4
Available-for-sale Securities, Unrecognized Loss	(2)
Available-for-sale Securities - Estimated Fair Value	5,673
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	4,275
Marketable securities	1,398
Available-for-sale Securities \| Corporate debt securities(1)
Debt Securities, Available-for-sale [Abstract]
Available-for-sale Securities - Carrying Amount	253
Available-for-sale Securities, Unrecognized Gain	0
Available-for-sale Securities, Unrecognized Loss	(2)
Available-for-sale Securities - Estimated Fair Value	251
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	15
Marketable securities	236
Available-for-sale Securities \| US Treasury and Government [Member]
Debt Securities, Available-for-sale [Abstract]
Available-for-sale Securities - Carrying Amount	5,418
Available-for-sale Securities, Unrecognized Gain	4
Available-for-sale Securities, Unrecognized Loss	0
Available-for-sale Securities - Estimated Fair Value	5,422
Debt Securities, Available-for-sale and Held-to-maturity [Abstract]
Cash and Cash Equivalents	4,260
Marketable securities	$ 1,162

Cash, Cash Equivalents, And Short-Term Investments, Accumulated Gross Unrealized Loss

No definition available.

Name:	jnj_CashCashEquivalentsAndShortTermInvestmentsAccumulatedGrossUnrealizedLoss
Namespace Prefix:	jnj_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash, Cash Equivalents, and Short-term Investments, Estimated Fair Value

+ References

No definition available.

+ Details

Name:	jnj_CashCashEquivalentsAndShortTermInvestmentsEstimatedFairValue
Namespace Prefix:	jnj_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash, Cash Equivalents, and Short-term Investments, Accumulated Gross Unrealized Gain

+ References

No definition available.

+ Details

Name:	jnj_CashCashEquivalentsandShorttermInvestmentsAccumulatedGrossUnrealizedGain
Namespace Prefix:	jnj_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount 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. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CashCashEquivalentsAndShortTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesClassifiedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in marketable security, classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_MarketableSecuritiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_HeldtomaturitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_SovereignDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=jnj_OtherReverseRepurchaseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_BankTimeDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: