AggregatePrincipalAmountOfNotesIssued

No definition available.

Name:	ck0001585389_Aggregateprincipalamountofnotesissued
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Credit facility cross default provision amount.

+ References

No definition available.

+ Details

Name:	ck0001585389_CreditFacilityCrossDefaultProvisionAmount
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest Accruing On Notes

+ References

No definition available.

+ Details

Name:	ck0001585389_InterestAccruingOnNotes
Namespace Prefix:	ck0001585389_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

LeverageRatio

+ References

No definition available.

+ Details

Name:	ck0001585389_Leverageratio
Namespace Prefix:	ck0001585389_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of credit facility additional borrowing capacity.

+ References

No definition available.

+ Details

Name:	ck0001585389_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility extension period.

+ References

No definition available.

+ Details

Name:	ck0001585389_LineOfCreditFacilityExtensionPeriod
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility sublimits.

+ References

No definition available.

+ Details

Name:	ck0001585389_LineOfCreditFacilitySublimits
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of operating properties.

+ References

No definition available.

+ Details

Name:	ck0001585389_NumberOfOperatingProperties
Namespace Prefix:	ck0001585389_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of prepay of debt instrument

+ References

No definition available.

+ Details

Name:	ck0001585389_Percentageofprepayofdebtinstrument
Namespace Prefix:	ck0001585389_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of reference rate used for variable rate of debt instrument.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: 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(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 3: 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(16))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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

- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ck0001585389_SSGTIIMergerAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=ck0001585389_KeyBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001585389_TwothousandthirtytwoprivateplacementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=ck0001585389_FourPointFiveThreePercentageSeniorNotesMember
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_DebtInstrumentAxis=ck0001585389_MidlandNorthCarolinaCmbsLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001585389_KeyBankSstIvCmbsLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ck0001585389_SstIvTcfLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=ck0001585389_SwinglineLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001585389_CreditFacilityTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001585389_AccordionFeatureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001585389_BMOLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ck0001585389_OakvilleIIIPropertyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=ck0001585389_CanadianDealerOfferedRatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=ck0001585389_CreditFacilityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Detail) $ in Millions				3 Months Ended	12 Months Ended
Debt - Additional Information (Detail) $ in Millions	Apr. 19, 2022 USD ($)	Oct. 07, 2021 USD ($)	Mar. 17, 2021 USD ($)	Mar. 31, 2023 USD ($) Property	Dec. 31, 2022 Property	May 25, 2022 USD ($)	Apr. 15, 2021	Mar. 16, 2021 USD ($)
Debt Instrument [Line Items]
Weighted average interest rate on debt				5.82%
Initial maximum amount available		$ 700
Number of operating properties \| Property				99
SSGT II Merger Agreement
Debt Instrument [Line Items]
Number of operating properties \| Property					10
Key Bank [Member]
Debt Instrument [Line Items]
Initial maximum amount available			$ 850					$ 500
Additional amount available under credit facility			350
Minimum
Debt Instrument [Line Items]
Credit facility cross default provision amount			$ 75
2032 Private Placement Notes
Debt Instrument [Line Items]
Interest rate	4.53%
Debt instrument, maturity date	Apr. 19, 2032
Aggregate principal amount of notes issued	$ 75					$ 75
Interest Accruing On Notes				5.28%
Prepayment of Notes	100.00%
Debt Instrument Fixed Rate				4.53%
2032 Private Placement Notes \| 4.53% Senior Notes[Member]
Debt Instrument [Line Items]
Debt issued	$ 150
2032 Private Placement Notes \| Maximum
Debt Instrument [Line Items]
Ratio of Total Indebtedness	0.0700
Leverage Ratio	7.00%
2032 Private Placement Notes \| Minimum
Debt Instrument [Line Items]
Ratio of Total Indebtedness	0.0100
Leverage Ratio	1.00%
Prepayment of Notes	5.00%
Midland North Carolina CMBS Loan
Debt Instrument [Line Items]
Number of operating properties \| Property					11
KeyBank SST IV CMBS Loan
Debt Instrument [Line Items]
Debt instrument, maturity date			Feb. 01, 2030
SST IV TCF Loan
Debt Instrument [Line Items]
Number of operating properties \| Property					5
Credit Facility Revolver
Debt Instrument [Line Items]
Line of credit facility, annual unused fee				230.00%
Line of credit facility, current borrowing capacity		450		$ 450
Increased the principal borrowing amount		200
Amount borrowed under the credit facility				$ 393
Credit Facility Revolver \| Key Bank [Member]
Debt Instrument [Line Items]
Outstanding balance on credit facility			$ 250
Maturity date			Mar. 17, 2024
Line of credit facility, term of extension options			1 year
Debt instrument, description of variable rate basis				185 basis points spread over Daily Simple SOFR plus an additional 10 basis points (the SOFR Index Adjustment) or 30-day CDOR
Credit Facility Revolver \| Maximum \| Key Bank [Member]
Debt Instrument [Line Items]
Line of credit facility, annual unused fee				0.25%
Credit Facility Revolver \| Maximum \| Key Bank [Member] \| Letter of Credit
Debt Instrument [Line Items]
Credit facility sublimits			$ 25
Credit Facility Revolver \| Maximum \| Key Bank [Member] \| Swingline Loans
Debt Instrument [Line Items]
Credit facility sublimits			25
Credit Facility Revolver \| Minimum \| Key Bank [Member]
Debt Instrument [Line Items]
Line of credit facility, annual unused fee				0.15%
Credit Facility Term Loan
Debt Instrument [Line Items]
Line of credit facility, annual unused fee				225.00%
Line of credit facility, current borrowing capacity				$ 250
Amount borrowed under the credit facility				$ 250
Credit Facility Term Loan \| Key Bank [Member]
Debt Instrument [Line Items]
Outstanding balance on credit facility			$ 250
Maturity date			Mar. 17, 2026
Line of credit facility, term of extension options			0 years
Debt instrument, description of variable rate basis				180 basis points spread over daily simple SOFR plus an additional 10 basis points (the "SOFR Index Adjustment") or 30-day Canadian dollar offered rate ("CDOR")
Accordion Feature
Debt Instrument [Line Items]
Initial maximum amount available		1,050
Additional amount available under credit facility		$ 350
BMO Loan \| Oakville III Property \| CDOR
Debt Instrument [Line Items]
Interest rate							2.25%
Credit facility agreement
Debt Instrument [Line Items]
Line of credit facility, annual unused fee				60.00%