Deferred Leasing Intangibles (Details) (USD $)	0 Months Ended	12 Months Ended			12 Months Ended				12 Months Ended									9 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2012	Jun. 11, 2012 sqft	Dec. 31, 2011	Dec. 31, 2012 Great Bend, KS	Dec. 31, 2012 Non-recurring Level 3 inputs	Dec. 31, 2012 In-place leases	Dec. 31, 2011 In-place leases	Dec. 31, 2012 In-place leases Great Bend, KS	Dec. 31, 2012 Above market leases	Dec. 31, 2011 Above market leases	Dec. 31, 2012 Tenant relationships	Dec. 31, 2011 Tenant relationships	Dec. 31, 2012 Leasing commissions	Dec. 31, 2011 Leasing commissions	Dec. 31, 2012 Below market leases	Dec. 31, 2011 Below market leases	Dec. 31, 2011 In-place leases, lease commissions and tenant relationships	Dec. 31, 2012 In-place leases, lease commissions and tenant relationships	Apr. 19, 2011 In-place leases, lease commissions and tenant relationships STAG Predecessor Group	Dec. 31, 2010 In-place leases, lease commissions and tenant relationships STAG Predecessor Group	Dec. 31, 2011 Above and below market leases	Dec. 31, 2012 Above and below market leases	Apr. 19, 2011 Above and below market leases STAG Predecessor Group	Dec. 31, 2010 Above and below market leases STAG Predecessor Group
Deferred leasing intangibles, assets
Gross							$ 108,363,000	$ 56,221,000		$ 50,699,000	$ 34,425,000	$ 61,050,000	$ 35,373,000	$ 23,376,000	$ 14,326,000
Less: Accumulated amortization							(28,289,000)	(13,741,000)		(10,362,000)	(4,722,000)	(11,298,000)	(4,673,000)	(5,984,000)	(3,916,000)
Net		187,555,000		113,293,000			80,074,000	42,480,000		40,337,000	29,703,000	49,752,000	30,700,000	17,392,000	10,410,000
Deferred leasing intangibles, liabilities
Gross																9,878,000	3,954,000
Less: Accumulated amortization																(3,007,000)	(2,025,000)
Net		6,871,000		1,929,000
Amortization expense																		12,900,000	25,000,000	700,000	3,500,000
Net increase (decrease) to rental revenues related to net amortization of above (below) market leases																						(2,800,000)	(4,800,000)	2,000	34,000
Estimated Net Amortization of In-Place Leases, Leasing Commissions and Tenant Relationships
2013																			32,851,000
2014																			27,559,000
2015																			21,831,000
2016																			18,164,000
2017																			13,907,000
Net Decrease (Increase) to Rental Income Related to Above and Below Market Leases
2013																							5,254,000
2014																							4,773,000
2015																							5,091,000
2016																							4,793,000
2017																							3,563,000
Net rentable square feet after exercise of option by tenant to downsize the space			60,000
Net rentable square feet before exercise of option by tenant to downsize the space			190,000
Discount rate at which cash flows are discounted (as a percent)	11.40%
Fair value of lease intangibles						400,000
Non-cash impairment loss		622,000				600,000
Non-cash impairment loss					$ 3,900,000				$ 700,000