Annual hurdle percentage.

No definition available.

Name:	ck1711929_AnnualHurdlePercentage
Namespace Prefix:	ck1711929_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual stockholder servicing fee percentage.

+ References

No definition available.

+ Details

Name:	ck1711929_AnnualStockholderServicingFeePercentage
Namespace Prefix:	ck1711929_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Leasing and legal service fees.

+ References

No definition available.

+ Details

Name:	ck1711929_LeasingAndLegalServiceFees
Namespace Prefix:	ck1711929_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of management fee on net asset value per annum.

+ References

No definition available.

+ Details

Name:	ck1711929_PercentageOfManagementFeeOnNetAssetValuePerAnnum
Namespace Prefix:	ck1711929_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Performance participation allocation.

+ References

No definition available.

+ Details

Name:	ck1711929_PerformanceParticipationAllocation
Namespace Prefix:	ck1711929_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Related party performance participation allocation percentage of annual return.

+ References

No definition available.

+ Details

Name:	ck1711929_RelatedPartyPerformanceParticipationAllocationPercentageOfAnnualReturn
Namespace Prefix:	ck1711929_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Services fee for accounting and administrative matters.

+ References

No definition available.

+ Details

Name:	ck1711929_ServicesFeeForAccountingAndAdministrativeMatters
Namespace Prefix:	ck1711929_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of common units issued of limited liability company (LLC).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonUnitIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

Name:	us-gaap_CostOfGoodsAndServicesSold
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of payable due to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04.12(3))
-URI http://asc.fasb.org/extlink&oid=120401414&loc=d3e603758-122996

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(3))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.17)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=124433192&loc=d3e56071-112765

+ Details

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

- Definition

The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

Name:	us-gaap_LegalFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expenses related to the managing member or general partner for management of the day-to-day business functions of the limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_ManagementFeeExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount of the unpaid portion of the fee payable to the managing member or general partner for management of the fund or trust.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow from the acquisition of property as primarily intended to generate income for its owner.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireCommercialRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=ck1711929_StarwoodCapitalLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ck1711929_AccruedStockholderServicingFeeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ck1711929_AdvancedOrganizationAndOfferingCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ck1711929_AccruedAffiliateServiceProviderExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=ck1711929_RentalPropertyOperatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalUnitsByClassAxis=ck1711929_ClassIUnitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ck1711929_UnregisteredClassISharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_StarwoodCapitalAndThirdPartyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_StarwoodREITSpecialLimitedPartnerLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_AllOtherUnitHoldersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_DealerManagerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ck1711929_ClassTClassSAndClassDSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_StarwoodREITAdvisorsLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ck1711929_AdvancedExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=ck1711929_OneMonthInArrearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck1711929_UnaffiliatedThirdPartyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_AffiliateServiceProviderExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ck1711929_AccruedAffiliateServiceProviderExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ck1711929_EssexServiceProviderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended
	May 10, 2022	Mar. 11, 2022	Apr. 30, 2022	Mar. 31, 2022	Mar. 31, 2021	Jan. 31, 2022	Dec. 31, 2021	Dec. 31, 2019
Related Party Transaction [Line Items]
Percentage of management fee on NAV per annum				1.25%
Management fees				$ 34,155	$ 7,420
Annual hurdle percentage				5.00%
Recognized liabilities for performance participation expense				$ 87,126	8,708
Due to affiliates				471,316			$ 513,268
Operating expenses				132,998	42,880
Leasing and legal service fees				0	0
Services fee for accounting and administrative matters				300	0
Dealer Manager
Related Party Transaction [Line Items]
Cost of legal services				100	0
Accrued Stockholder Servicing Fee
Related Party Transaction [Line Items]
Due to affiliates				365,592			291,544
Advanced Organization And Offering Costs
Related Party Transaction [Line Items]
Due to affiliates				4,009			4,373
Accrued Affiliate Service Provider Expenses
Related Party Transaction [Line Items]
Due to affiliates				1,002			843
Accrued Affiliate Service Provider Expenses \| Rental property operating
Related Party Transaction [Line Items]
Operating expenses				$ 2,800	1,300
Class I Unit
Related Party Transaction [Line Items]
Units issued as payment for performance participation allocation						7,872,930
Subsequent Event
Related Party Transaction [Line Items]
Purchase Price	$ 3,500,000
Unregistered Class I shares
Related Party Transaction [Line Items]
Stock issued as management fees, shares				824,691
Management fees, accrued				$ 12,400
Unregistered Class I shares \| Subsequent Event
Related Party Transaction [Line Items]
Stock issued as management fees, shares			457,388
Starwood Capital And Third Party
Related Party Transaction [Line Items]
Purchase Price		$ 109,200
Special Limited Partner
Related Party Transaction [Line Items]
Related party allocation percentage of annual total return				12.50%
All Other Unit Holders [Member]
Related Party Transaction [Line Items]
Related party allocation percentage of annual total return				87.50%
Dealer Manager \| Common Stock Class T, Class S and Class D \| Accrued Stockholder Servicing Fee
Related Party Transaction [Line Items]
Due to affiliates				$ 365,600			291,500
Dealer Manager \| Common Stock Class T, Class S and Class D \| Accrued Stockholder Servicing Fee \| Maximum
Related Party Transaction [Line Items]
Annual stockholder servicing fee percentage				8.75%
Advisor \| Advanced Organization And Offering Costs
Related Party Transaction [Line Items]
Due to affiliates								$ 7,300
Advisor \| Advanced Expenses \| One Month in Arrears
Related Party Transaction [Line Items]
Due to affiliates				$ 5,000			6,700
Advisor \| Advanced Expenses \| Unaffiliated Third Party
Related Party Transaction [Line Items]
Due to affiliates				100			$ 100
Affiliate Service Provider Expenses
Related Party Transaction [Line Items]
Cost of legal services				200	100
Accrued Affiliate Service Provider Expenses \| Essex Service Provider
Related Party Transaction [Line Items]
Cost of legal services				$ 1,100	$ 0