GOODWILL (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill, beginning balance	$ 2,188
Goodwill, ending balance	$ 2,371	$ 2,188
Number of Cash Generating Units \| item	4
Reconstruction
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill, beginning balance	$ 551
Goodwill, ending balance	$ 566	551
Pre-tax discount rate	10.00%
Increase in discount rates	29.50%
Reconstruction \| Minimium
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	1.00%
Reconstruction \| Maximum
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	10.60%
Reconstruction \| Weighted average
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	2.00%
Other Surgical Devices
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill, beginning balance	$ 1,351
Goodwill, ending balance	$ 1,501	1,351
Pre-tax discount rate	10.00%
Increase in discount rates	16.60%
Other Surgical Devices \| Minimium
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	1.00%
Other Surgical Devices \| Maximum
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	9.00%
Other Surgical Devices \| Weighted average
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	2.00%
Advanced Wound Management
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill, beginning balance	$ 286
Goodwill, ending balance	$ 304	286
Pre-tax discount rate	10.00%
Increase in discount rates	26.30%
Advanced Wound Management \| Minimium
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	2.00%
Advanced Wound Management \| Maximum
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	17.30%
Advanced Wound Management \| Weighted average
Disclosure of reconciliation of changes in goodwill [line items]
Revenue growth rates	2.00%
Cost
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill, beginning balance	$ 2,188	2,012
Exchange adjustment	51	(35)
Acquisitions	132	211
Goodwill, ending balance	$ 2,371	$ 2,188

The amount of additional goodwill recognised, except goodwill included in a disposal group that, on acquisition, meets the criteria to be classified as held for sale in accordance with IFRS 5. [Refer: Goodwill; Disposal groups classified as held for sale [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B67
-Subparagraph d
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B67_d_ii&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_AdditionalRecognitionGoodwill
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The discount rate applied to cash flow projections for a cash-generating unit (group of units). [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph d
-Clause v
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_d_v&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph e
-Clause v
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_e_v&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The growth rate used to extrapolate cash flow projections beyond the period covered by the most recent budgets/forecasts for a cash-generating unit (group of units). [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph d
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_d_iv&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph e
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_e_iv&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_DescriptionOfGrowthRateUsedToExtrapolateCashFlowProjections
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfReconciliationOfChangesInGoodwillLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of assets representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognised. [Refer: Business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B67
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B67_d&doctype=Appendix&seq=2
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 134
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_134_a&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 135
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_135_a&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_c&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_Goodwill
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The increase (decrease) in goodwill resulting from net exchange differences arising on the translation of the financial statements from the functional currency into a different presentation currency, including the translation of a foreign operation into the presentation currency of the reporting entity. [Refer: Goodwill]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B67
-Subparagraph d
-Clause vi
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B67_d_vi&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesGoodwill
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase in discount rate applied to cash flow projections for a cash-generating unit

+ References

No definition available.

+ Details

Name:	snn_DescriptionOfIncreaseInDiscountRatesAppliedToCashFlowProjections
Namespace Prefix:	snn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Cash Generating Units identified by the company

+ References

No definition available.

+ Details

Name:	snn_NumberOfCashGeneratingUnits
Namespace Prefix:	snn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsAxis=snn_ReconstructionCguMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsAxis=snn_OtherSurgicalDevicesCguMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsAxis=snn_AdvancedWoundManagementCguMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis=ifrs-full_GrossCarryingAmountMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: