CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities
Net income	$ 20,189,611	$ 18,603,594	$ 9,889,537
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation	6,996,741	5,792,281	6,055,225
Amortization	2,483,217	1,712,530	1,105,087
Stock-based compensation	1,812,532	1,657,209	1,364,280
Impairment charge	450,000	0	13,500,000
Gain on extinguishment of debt	0	0	(2,360,231)
Gain on sale of assets	(946,347)	(2,097,105)	(110,212)
(Increase) decrease in accounts receivable	(1,102,713)	(1,358,374)	528,448
(Increase) decrease in other assets	(780,069)	(864,294)	8,072
(Decrease) increase in accounts payable	838,515	(1,358,147)	1,951,420
Decrease in deferred revenue	(463,380)	(463,380)	(6,951,591)
Increase (decrease) in accrued interest	135,446	(398,779)	513,041
Increase (decrease) in tenant deposits	(23,814)	(19,814)	3,873
Net Cash Provided by Operating Activities	29,589,739	21,205,721	25,496,949
Cash Flows from Investing Activities
Acquisition of real estate investments	(75,920,083)	(64,166,390)	(35,657,158)
Development of real estate investments and other (including capitalized interest of $566,793 in 2013, $149,054 in 2012, and $0 in 2011)	(14,619,386)	(20,349,688)	(1,456,455)
Payment of leasing costs	(183,310)	(55,960)	(197,259)
Net proceeds from sale of assets	5,462,280	15,315,728	8,058,520
Net Cash Used In Investing Activities	(85,260,499)	(69,256,310)	(29,252,352)
Cash Flows from Financing Activities
Proceeds from common stock offering, net	93,393,056	35,042,235	0
Unsecured revolving credit facility borrowings	106,189,924	101,220,945	119,244,291
Unsecured revolving credit facility repayments	(140,219,929)	(114,134,838)	(91,180,647)
Mortgage notes payable proceeds	0	48,640,000	0
Payments of mortgage notes payable	(3,478,383)	(3,164,654)	(4,229,352)
Term loan payable proceeds	35,000,000	0	0
Dividends paid	(20,859,476)	(17,663,808)	(16,803,705)
Limited partners' distributions paid	(566,619)	(556,188)	(594,427)
Repayments of payables for capital expenditures	(122,080)	(424,321)	(286,078)
Payments for financing costs	(398,879)	(1,641,418)	(985,297)
Net Cash Provided by Financing Activities	68,937,614	47,317,953	5,164,785
Net Increase (Decrease) in Cash and Cash Equivalents	13,266,854	(732,636)	1,409,382
Cash and Cash Equivalents, beginning of period	1,270,027	2,002,663	593,281
Cash and Cash Equivalents, end of period	14,536,881	1,270,027	2,002,663
Supplemental Disclosure of Cash Flow Information
Cash paid for interest (net of amounts capitalized)	6,149,649	4,722,042	4,458,292
Cash paid (refunded) for income tax	(21,543)	318,289	220,202
Supplemental Disclosure of Non-Cash Investing and Financing Activities
Shares issued under Stock Incentive Plan	2,401,688	2,175,831	2,312,056
Dividends and limited partners' distributions declared and unpaid	6,243,933	4,710,446	4,070,690
Forgiveness of mortgage debt	0	9,173,789	0
Real estate acquisitions financed with debt assumption	$ 0	$ 18,220,528	$ 3,403,603