Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 1,368	$ (9,941)	$ 1,437	$ 2,391
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			72,100	60,236
Asset Impairment Charges	0	11,231	0	11,231
Loss on Involuntary Conversion			330	0
Non-cash portion of interest expense			980	780
Intangible amortization in rental income, net			2,555	3,187
Straight-line rent adjustments, net			(2,778)	(1,293)
Restricted Stock Award, Forfeitures, Dividends			2	3
Loss on extinguishment of debt	2	839	2	1,973
Gain on the sales of rental property, net			(1,662)	(20,946)
Non-cash compensation expense			4,775	5,649
Change in assets and liabilities:
Tenant accounts receivable, net			1,362	752
Restricted cash			73	(366)
Prepaid expenses and other assets			(6,317)	(3,693)
Accounts payable, accrued expenses and other liabilities			(543)	1,949
Tenant prepaid rent and security deposits			4,110	(93)
Total adjustments			74,989	59,369
Net cash provided by operating activities			76,426	61,760
Cash flows from investing activities:
Acquisitions of land and buildings and improvements			(303,624)	(70,875)
Additions of land and building and improvements			(14,238)	(11,201)
Proceeds from Sale of Buildings			10,309	48,670
Proceeds from Insurance Settlement, Investing Activities			639	0
Restricted cash			757	(5,805)
Acquisition deposits, net			820	(556)
Acquisitions of deferred leasing intangibles			(62,782)	(14,992)
Net cash used in investing activities			(368,119)	(54,759)
Cash flows from financing activities:
Proceeds from sale of series C preferred stock			0	75,000
Proceeds from unsecured credit facility			356,000	152,000
Repayment of unsecured credit facility			(254,000)	(144,000)
Repayment of mortgage notes			(17,033)	(31,955)
Payment of loan fees and costs			(43)	(73)
Payments of Debt Extinguishment Costs			(2)	(1,969)
Payments of Dividends			67,388	57,360
Proceeds from sales of common stock			274,385	0
Payments Related to Tax Withholding for Share-based Compensation			(969)	0
Offering costs			(3,773)	(2,650)
Net cash provided by (used in) financing activities			287,177	(11,007)
Decrease in cash and cash equivalents			(4,516)	(4,006)
Cash and cash equivalents—beginning of period			12,192	12,011	$ 12,011
Cash and cash equivalents—end of period	7,676	8,005	7,676	8,005	12,192
Supplemental disclosure:
Cash paid for interest, net of capitalized interest			20,479	18,627
Supplemental schedule of non-cash investing and financing activities
Other Significant Noncash Transaction, Value of Consideration Given			18,558	0
stag_Additionstobuildingandbuildingimprovements			503	1,004
Noncash or Part Noncash Acquisition, Fixed Assets Acquired			16,986	174
Acquisitions of deferred leasing intangibles			(2,001)	(44)
Partial Disposal of Building Due to Involuntary Conversion			424	0
Investing Other Receivables Due to Involuntary Conversion			(424)	0
Change in additions of land, building, and improvements included in accounts payable, accrued expenses, and other liabilities			(1,572)	(1,207)
Additions to building and other capital improvements from non-cash compensation			(16)	(13)
Change in loan fees, costs, and offering costs included in accounts payable, accrued expenses, and other liabilities			(141)	58
Dividends and distributions declared but not paid	$ 11,153	$ 8,327	$ 11,153	$ 8,327	$ 9,728