Organization and Description of Business (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Organization and Description of Business
Number of property owned	179
Number of states in which the entity owned properties	33
Area of property (in square feet)	31,200,000
Number of warehouse/distribution properties	119
Number of light manufacturing properties	39
Number of flex/office properties	21
Percentage of properties leased to tenants	95.40%
Number of tenants to whom properties are given on lease	161
STAG Industrial Operating Partnership, L.P.
Organization and Description of Business
Ownership interest in Operating Partnership (as a percent)	86.94%	85.29%