Deferred Leasing Intangibles (Details) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended			1 Months Ended												3 Months Ended		6 Months Ended	1 Months Ended	3 Months Ended			6 Months Ended	1 Months Ended	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2012	Jun. 11, 2012 sqft	Dec. 31, 2011	Jun. 30, 2012 Non recurring Level 3 inputs	Jun. 11, 2012 Non recurring Level 3 inputs	Jun. 30, 2012 In-place leases	Dec. 31, 2011 In-place leases	Jun. 30, 2012 Above market leases	Dec. 31, 2011 Above market leases	Jun. 30, 2012 Tenant relationships	Dec. 31, 2011 Tenant relationships	Jun. 30, 2012 Leasing commissions	Dec. 31, 2011 Leasing commissions	Jun. 30, 2012 Below market leases	Dec. 31, 2011 Below market leases	Jun. 30, 2011 In-place leases, lease commissions and tenant relationships	Jun. 30, 2012 In-place leases, lease commissions and tenant relationships	Jun. 30, 2012 In-place leases, lease commissions and tenant relationships	Apr. 19, 2011 In-place leases, lease commissions and tenant relationships STAG Predecessor Group	Apr. 19, 2011 In-place leases, lease commissions and tenant relationships STAG Predecessor Group	Jun. 30, 2011 Above and below market leases	Jun. 30, 2012 Above and below market leases	Jun. 30, 2012 Above and below market leases	Apr. 19, 2011 Above and below market leases STAG Predecessor Group	Apr. 19, 2011 Above and below market leases STAG Predecessor Group
Deferred leasing intangibles, assets
Gross								$ 72,089,000	$ 56,221,000	$ 40,409,000	$ 34,425,000	$ 41,164,000	$ 35,373,000	$ 14,750,000	$ 14,326,000
Less: Accumulated amortization								(19,779,000)	(13,741,000)	(7,258,000)	(4,722,000)	(7,609,000)	(4,673,000)	(4,965,000)	(3,916,000)
Net	128,801,000	128,801,000	128,801,000		113,293,000			52,310,000	42,480,000	33,151,000	29,703,000	33,555,000	30,700,000	9,785,000	10,410,000
Deferred leasing intangibles, liabilities
Gross																6,784,000	3,954,000
Less: Accumulated amortization																(2,334,000)	(2,025,000)
Net	4,450,000	4,450,000	4,450,000		1,929,000											4,450,000	1,929,000
Amortization expense																		3,700,000	5,100,000	10,100,000	100,000	700,000
Net increase (decrease) to rental revenues related to net amortization of above (below) market leases																							(900,000)	(1,100,000)	(2,300,000)	(2,000)	2,000
Estimated Net Amortization of In-Place Leases, Leasing Commissions and Tenant Relationships
Remainder of 2012																			10,267,000	10,267,000
2013																			17,003,000	17,003,000
2014																			15,304,000	15,304,000
2015																			13,279,000	13,279,000
2016																			11,369,000	11,369,000
Net Decrease (Increase) to Rental Income Related to Above and Below Market Leases
Remainder of 2012																									2,401,000
2013																									4,499,000
2014																									4,126,000
2015																									3,953,000
2016																									3,840,000
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
Noncash impairment loss		$ 622,000	$ 622,000			$ 600,000