Debt instrument conversion expenses.

No definition available.

Name:	smrt_DebtInstrumentConversionExpenses
Namespace Prefix:	smrt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line of credit facility expiration month year.

+ References

No definition available.

+ Details

Name:	smrt_LineOfCreditFacilityExpirationMonthYear
Namespace Prefix:	smrt_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility extended expiration month year.

+ References

No definition available.

+ Details

Name:	smrt_LineOfCreditFacilityExtendedExpirationMonthYear
Namespace Prefix:	smrt_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility first required payment month year.

+ References

No definition available.

+ Details

Name:	smrt_LineOfCreditFacilityFirstRequiredPaymentMonthYear
Namespace Prefix:	smrt_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

+ Details

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

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870

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

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- 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 http://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 http://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 http://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 http://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 http://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 http://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

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

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

+ Details

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

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12355-112629

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12317-112629

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

+ Details

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

- Definition

Description of the conditions for borrowing under the credit facility including the nature of any restrictions.

+ References

+ Details

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

- Definition

Description of the frequency of the required periodic payments of interest, principal, or both, and the amount, if set, or a description of a formula upon which payment is based.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityFrequencyOfPaymentAndPaymentTerms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_ConvertibleDebtMember
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_CreditFacilityAxis=smrt_TermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	smrt_RevolvingCreditFacilityAxis=smrt_SublimitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Debt - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
Debt - Additional Information (Details) - USD ($)	Dec. 31, 2021	Aug. 31, 2019	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Sep. 07, 2021	Feb. 29, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity		$ 15,000,000
Credit facility, frequency of payment and payment terms, description				The Term Loan Facility was subject to monthly payments of interest, in arrears, accrued on the principal balance of the Term Loan Facility through November 2020. Thereafter, and continuing through the Term Loan Facility maturity date, the Term Loan Facility was subject to equal monthly payments of principal plus accrued interest.
Common stock, issued	193,864			193,864	10,376	147,911
Credit facility, covenant terms, description				The Senior Revolving Facility contains certain customary affirmative and negative covenants and events of default. Such covenants will, among other things, restrict, subject to certain exceptions, the Company’s ability to (i) engage in certain mergers or consolidations, (ii) sell, lease or transfer all or substantially all of the Company’s assets, (iii) engage in certain transactions with affiliates, (iv) make changes in the nature of the Company’s business and our subsidiaries, and (v) incur additional indebtedness that is secured on a pari passu basis with the Senior Revolving Facility.
Gain (Loss) on extinguishment of debt				$ (27,000)	$ (164,000)
February Two Thousand and Twenty Convertible Note
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage							5.00%
Debt instrument principal amount							$ 50,000
December Two Thousand and Nineteen Convertible Note
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage								5.00%
Debt instrument principal amount								$ 7,500,000
Conversion of December Two Thousand and Nineteen Convertible Note to Series C One Preferred Stock
Debt Instrument [Line Items]
Debt Instrument convertible conversion price			$ 10.02
Number of shares issued on conversion of debt			756,000
Gain (Loss) on extinguishment of debt					$ 164,000
Conversion of February Two Thousand and Twenty Convertible Note to Series C One Preferred Stock
Debt Instrument [Line Items]
Debt Instrument convertible conversion price			$ 10.01
Number of shares issued on conversion of debt			5,000
Convertible Debt
Debt Instrument [Line Items]
Debt instrument conversion expenses				0
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity		$ 10,000,000
Line of credit facility expiration month year		2021-08
Line of credit facility expiration month year, extended		2021-12
Term Loan Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity		$ 5,000,000
Line of credit facility expiration month year		2023-11
Line of credit facility first required payment month year		2020-11
Senior Revolving Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 75,000,000			75,000,000
Line of credit facility expiration month year	2026-12
Debt instrument term	5 years
Line of credit facility unused capacity commitment fee percentage	0.25%
Debt instrument principal amount	$ 0			0
Debt issuance costs	$ 658,000			658,000
Senior Revolving Facility \| ABR Loan
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	0.50%
Senior Revolving Facility \| SOFR Loan
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	0.10%
Senior Revolving Facility \| Base Rate \| SOFR Loan
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	0.00%
Senior Revolving Facility \| Federal Funds \| ABR Loan
Debt Instrument [Line Items]
Debt instrument basis spread on variable rate	3.25%
Letter of Credit \| Sublimit
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 10,000,000			10,000,000
Swingline \| Sublimit
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 10,000,000			$ 10,000,000