Debt Instrument, Prepayment Penalty, Period Without Penalty

No definition available.

Name:	stag_DebtInstrumentPrepaymentPenaltyPeriodWithoutPenalty
Namespace Prefix:	stag_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative notional amount swapped

+ References

No definition available.

+ Details

Name:	stag_DerivativeNotionalAmountSwapped
Namespace Prefix:	stag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Extension Period

+ References

No definition available.

+ Details

Name:	stag_ExtensionPeriod
Namespace Prefix:	stag_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number Of Extensions

+ References

No definition available.

+ Details

Name:	stag_NumberOfExtensions
Namespace Prefix:	stag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- 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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: 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 http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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

Reference 4: 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 http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
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 http://asc.fasb.org/extlink&oid=120520924&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 http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num: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:	num: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 CCYY-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 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 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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

- Definition

Amount, after accumulated amortization, of debt premium.

+ References

Reference 1: 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 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

+ Details

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

- 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://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=119993939&loc=d3e28555-108399

+ Details

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

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: 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(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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(16))
-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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A300MillionUnsecuredTermLoanGMember
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_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LongTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A150MillionUnsecuredTermLoanCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A150MillionUnsecuredTermLoanBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A150MillionUnsecuredTermLoanAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A150MillionUnsecuredTermLoanDMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A175MillionUnsecuredTermLoanEMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A200MillionUnsecuredTermLoanFMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A100MillionSeriesFUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A50MillionSeriesAUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A100MillionSeriesDUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A75MillionSeriesGUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A50MillionSeriesBUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A80MillionSeriesCUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A20MillionSeriesEUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_A100MillionSeriesHUnsecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=stag_ThriventFinancialforLutheransDueDecember152023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Summary (Details) $ in Thousands	9 Months Ended
Debt - Summary (Details) $ in Thousands	Sep. 30, 2020 USD ($) extention	Mar. 19, 2021	Apr. 17, 2020 USD ($) extention	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,602,600			$ 1,651,085
Unamortized debt issuance costs	(6,389)			(6,111)
Unamortized fair market value premium	31			39
Principal outstanding	$ 1,596,242			1,645,013
Weighted average interest rate	3.62%
Interest Rate Swaps
Debt Instrument [Line Items]
Derivative notional amount swapped	$ 975,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Stated interest rate	0.14825%
Term Loan \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
$300 Million Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt, gross			$ 300,000
Number Of Extensions \| extention			2
Debt Instrument Term Extension Period	1 year
$300 Million Unsecured Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
$300 Million Unsecured Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Unsecured Credit Facility
Debt Instrument [Line Items]
Principal outstanding	$ 0			146,000
Debt Instrument, Maturity Date	Jan. 12, 2024
Maximum borrowing capacity	$ 500,000
Number Of Extensions \| extention	2
Debt Instrument Term Extension Period	6 months
Unsecured Credit Facility \| Prepaid Expenses and Other Assets
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (1,800)			(2,400)
Unsecured Credit Facility \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Unsecured Term Loans
Debt Instrument [Line Items]
Long-term debt, gross	$ 975,000			875,000
Unamortized debt issuance costs	(4,304)			(3,625)
Principal outstanding	970,696			871,375
Unsecured Term Loans \| $150 Million Wells Fargo Unsecured Term Loan C
Debt Instrument [Line Items]
Long-term debt, gross	$ 0			150,000
Debt Instrument, Interest Rate, Effective Percentage	2.39%
Debt Instrument, Maturity Date	Sep. 29, 2020
Unsecured Term Loans \| $150 Million Wells Fargo Unsecured Term Loan B
Debt Instrument [Line Items]
Long-term debt, gross	$ 0			150,000
Debt Instrument, Interest Rate, Effective Percentage	3.05%
Debt Instrument, Maturity Date	Mar. 21, 2021
Unsecured Term Loans \| $150 Million Wells Fargo Unsecured Term Loan A
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000			150,000
Debt Instrument, Interest Rate, Effective Percentage	3.38%
Debt Instrument, Maturity Date	Mar. 31, 2022
Fixed Interest Rate (as a percent)	2.38%
Unsecured Term Loans \| $150 Million Unsecured Term Loan D [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000			150,000
Debt Instrument, Interest Rate, Effective Percentage	2.85%
Debt Instrument, Maturity Date	Jan. 04, 2023
Fixed Interest Rate (as a percent)	1.85%
Unsecured Term Loans \| $300 Million Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 300,000			0
Debt Instrument, Interest Rate, Effective Percentage	2.77%
Debt Instrument, Maturity Date	Apr. 18, 2023
Fixed Interest Rate (as a percent)	1.17%
Unsecured Term Loans \| $300 Million Unsecured Term Loan [Member] \| Scenario, Forecast [Member]
Debt Instrument [Line Items]
Fixed Interest Rate (as a percent)		0.28%
Unsecured Term Loans \| $175 Million Unsecured Term Loan E [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 175,000			175,000
Debt Instrument, Interest Rate, Effective Percentage	3.92%
Debt Instrument, Maturity Date	Jan. 15, 2024
Fixed Interest Rate (as a percent)	2.92%
Unsecured Term Loans \| $200 Million Unsecured Term Loan F [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 200,000			100,000
Debt Instrument, Interest Rate, Effective Percentage	3.11%
Debt Instrument, Maturity Date	Jan. 12, 2025
Fixed Interest Rate (as a percent)	2.11%
Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 575,000			575,000
Unamortized debt issuance costs	(1,819)			(2,117)
Principal outstanding	573,181			572,883
Unsecured Notes \| $100 Million Series F Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000			100,000
Stated interest rate	3.98%
Debt Instrument, Maturity Date	Jan. 05, 2023
Unsecured Notes \| $50 Million Series A Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000			50,000
Stated interest rate	4.98%
Debt Instrument, Maturity Date	Oct. 01, 2024
Unsecured Notes \| $100 Million Series D Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000			100,000
Stated interest rate	4.32%
Debt Instrument, Maturity Date	Feb. 20, 2025
Unsecured Notes \| $75 Million Series G Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 75,000			75,000
Stated interest rate	4.10%
Debt Instrument, Maturity Date	Jun. 13, 2025
Unsecured Notes \| $50 Million Series B Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000			50,000
Stated interest rate	4.98%
Debt Instrument, Maturity Date	Jul. 01, 2026
Unsecured Notes \| $80 Million Series C Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 80,000			80,000
Stated interest rate	4.42%
Debt Instrument, Maturity Date	Dec. 30, 2026
Unsecured Notes \| $20 Million Series E Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 20,000			20,000
Stated interest rate	4.42%
Debt Instrument, Maturity Date	Feb. 20, 2027
Unsecured Notes \| $100 Million Series H Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000			100,000
Stated interest rate	4.27%
Debt Instrument, Maturity Date	Jun. 13, 2028
Mortgage Loans Payable
Debt Instrument [Line Items]
Long-term debt, gross	$ 52,600			55,085
Unamortized debt issuance costs	(266)			(369)
Unamortized fair market value premium	31			39
Principal outstanding	52,365			54,755
Mortgage Loans Payable \| Wells Fargo Bank, National Association CMBS Loan
Debt Instrument [Line Items]
Long-term debt, gross	$ 49,013			51,406
Stated interest rate	4.31%
Debt Instrument, Maturity Date	Dec. 01, 2022
Penalty free prepayment period	3 months
Mortgage Loans Payable \| Thrivent Financial for Lutherans Due December 15, 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 3,587			$ 3,679
Stated interest rate	4.78%
Debt Instrument, Maturity Date	Dec. 15, 2023
Penalty free prepayment period	3 months