Name:	stag_SharebasedCompensationArrangementbySharebasedPaymentAwardAllocationforTotalStockholderReturnComparedtoIndex
Namespace Prefix:	stag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Allocation for Total Stockholder Return Compared to Industry Peer Group

No definition available.

Name:	stag_SharebasedCompensationArrangementbySharebasedPaymentAwardAllocationforTotalStockholderReturnComparedtoIndustryPeerGroup
Namespace Prefix:	stag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Allocation for Total Stockholder Return Compared to Size-Based Peer Group

No definition available.

Name:	stag_SharebasedCompensationArrangementbySharebasedPaymentAwardAllocationforTotalStockholderReturnComparedtoSizeBasedPeerGroup
Namespace Prefix:	stag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Percent of Target Units Awarded

No definition available.

Name:	stag_SharebasedCompensationArrangementbySharebasedPaymentAwardPercentofTargetUnitsAwarded
Namespace Prefix:	stag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation by Share-based Payment Award, Fair Value Assumptions, Estimated Fair Value

No definition available.

Name:	stag_SharebasedCompensationbySharebasedPaymentAwardFairValueAssumptionsEstimatedFairValue
Namespace Prefix:	stag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Share-based Compensation by Share-based Payment Award, Number of Benchmarks

No definition available.

Name:	stag_SharebasedCompensationbySharebasedPaymentAwardNumberofBenchmarks
Namespace Prefix:	stag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

No definition available.

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

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The risk-free interest rate assumption that is used in valuing an option on its own shares.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

Percentage of vesting of share-based compensation awards.

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_PlanNameAxis=stag_EquityIncentivePlan2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardDateAxis=stag_Awardedin2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_VestingAxis=stag_ShareBasedCompensationAwardTrancheFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: