Stockholders' Equity (Details)				3 Months Ended				6 Months Ended	12 Months Ended
	Jun. 04, 2021 USD ($)	May 20, 2021 USD ($) shares	Jun. 04, 2020 shares	Jun. 30, 2021 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares	Mar. 31, 2020 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) item shares	Dec. 31, 2020 USD ($) shares
Stockholders' Equity
Common Stock, Shares, Outstanding | shares				107,394,763				107,394,763	107,328,199
Dividends declared and paid
Cash dividend declared per share (in dollars per share) | $ / shares				$ 0.09	$ 0.09	$ 0.09	$ 0.09
Total Dividends | $				$ 9,659,000	$ 9,660,000	$ 9,654,000	$ 9,654,000
General and Administrative Expense [Member]
Equity-Based Compensation
Compensation cost | $	$ 337,500	$ 337,500
2002 Stock Incentive Plan
Equity-Based Compensation
Maximum number of shares provided for grant under equity-based incentive compensation plan | shares				2,000,000				2,000,000
Number of vesting requirements | item								0
Number of shares available for grant under the plan, Beginning | shares					1,847,384		1,906,382	1,847,384	1,906,382
Shares Granted | shares		(66,564)	(58,998)					(66,564)	(58,998)
Number of shares available for grant under the plan, Ending | shares				1,780,820				1,780,820	1,847,384
Compensation Cost, Beginning | $					$ 675,000		$ 337,500	$ 675,000	$ 337,500
Compensation cost | $								337,500	337,500
Compensation Cost, Ending | $				$ 1,012,500				$ 1,012,500	$ 675,000