Summary of Significant Accounting Policies (Details 3) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Income Taxes
State and local income, excise and franchise taxes	$ 100,000	$ 100,000
Liabilities for uncertain tax positions	$ 0

Represents the current and noncurrent portion of the amount recognized for uncertain tax positions as of the balance sheet date.

No definition available.

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