CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows from Operating Activities
Net income	$ 39,762,455	$ 18,913,009	$ 20,189,611
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,529,629	8,486,178	6,996,741
Amortization	4,956,245	2,616,533	1,746,792
Amortization from financing and credit facility costs	689,321	950,876	736,425
Stock-based compensation	1,992,241	1,986,835	1,812,532
Impairment charge	0	3,020,000	450,000
Loss on extinguishment of debt	179,867	0	0
(Gain) loss on sale of assets	(12,135,036)	404,996	(946,347)
Increase in accounts receivable	(2,910,592)	(1,244,967)	(1,102,713)
(Increase) decrease in other assets	(197,380)	346,131	(780,069)
Increase (decrease) in accounts payable	1,043,064	(311,337)	716,435
Decrease in deferred revenue	(463,380)	(463,380)	(463,380)
Increase (decrease) in accrued interest	241,366	250,597	135,446
Decrease in tenant deposits	(7,548)	(4,491)	(23,814)
Net Cash Provided by Operating Activities	44,680,252	34,950,980	29,467,659
Cash Flows from Investing Activities
Acquisition of real estate investments	(223,870,660)	(143,272,607)	(75,920,083)
Development of real estate investments and other (including capitalized interest of $39,325 in 2015, $263,472 in 2014, and $566,793 in 2013)	(6,970,271)	(16,526,566)	(14,619,386)
Payment of leasing costs	(66,410)	(354,336)	(183,310)
Net proceeds from sale of assets	28,132,261	12,455,673	5,462,280
Net Cash Used In Investing Activities	(202,775,080)	(147,697,836)	(85,260,499)
Cash Flows from Financing Activities
Proceeds from common stock offering, net	92,259,603	73,302,116	93,393,056
Unsecured revolving credit facility borrowings	161,000,000	148,622,976	106,189,924
Unsecured revolving credit facility repayments	(158,000,000)	(143,122,976)	(140,219,929)
Payments of mortgage notes payable	(5,177,870)	(12,766,704)	(3,478,383)
Term loan payable proceeds	0	65,000,000	35,000,000
Senior unsecured notes proceeds	100,000,000	0	0
Dividends paid	(32,992,155)	(25,402,637)	(20,859,476)
Limited partners' distributions paid	(636,143)	(590,951)	(566,619)
Debt extinguishment costs	(150,085)	0	0
Payments for financing costs	(896,392)	(1,432,391)	(398,879)
Net Cash Provided by Financing Activities	155,406,958	103,609,433	69,059,694
Net (Decrease) Increase in Cash and Cash Equivalents	(2,687,870)	(9,137,423)	13,266,854
Cash and Cash Equivalents, beginning of period	5,399,458	14,536,881	1,270,027
Cash and Cash Equivalents, end of period	2,711,588	5,399,458	14,536,881
Supplemental Disclosure of Cash Flow Information
Cash paid for interest (net of amounts capitalized)	11,548,099	7,824,594	6,149,649
Cash paid (refunded) for income tax	924	(355)	(21,543)
Supplemental Disclosure of Non-Cash Investing and Financing Activities
Shares issued under equity incentive plans	2,863,766	2,390,245	2,401,688
Dividends and limited partners' distributions declared and unpaid	9,757,988	8,048,404	6,243,933
Real estate acquisitions financed with debt assumption	0	5,631,183	0
Real estate investment financed with accounts payable	$ 122,495	$ 0	$ 0