Stockholders' Equity - Dividend distributions (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Dividends Payable [Line Items]
Dividends	$ 1,374,127	$ 1,144,561	$ 871,969	$ 693,183	$ 581,813	$ 508,396	$ 427,589	$ 346,034	$ 4,083,840	$ 1,863,832
Cash
Dividends Payable [Line Items]
Dividends	745,566	498,717	387,574	304,955	236,895	215,317	182,226	153,832	1,936,812	788,270
DRP & Stock
Dividends Payable [Line Items]
Dividends	$ 628,561	$ 645,844	$ 484,395	$ 388,228	$ 344,918	$ 293,079	$ 245,363	$ 192,202	$ 2,147,028	$ 1,075,562