Federal Income Taxes - Tax Status of Dividends (Details) - $ / shares	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Total (in dollars per share)	$ 0.29	$ 0.28	$ 0.29	$ 1.13	$ 1.09
Characterization Of Distributions For Federal Income Tax Purposes
Income Tax Contingency [Line Items]
Qualified dividend (in dollars per share)			0	0	0
Capital gain (in dollars per share)			0.060	0.240	0
Total (in dollars per share)			$ 0.580	$ 1.060	$ 0.870
Qualified dividend			0.00%	0.00%	0.00%
Capital gain			10.00%	23.00%	0.00%
Total			100.00%	100.00%	100.00%
Non-Section 199A | Characterization Of Distributions For Federal Income Tax Purposes
Income Tax Contingency [Line Items]
Ordinary income (in dollars per share)			$ 0	$ 0	$ 0
Ordinary income			0.00%	0.00%	0.00%
Section 199A | Characterization Of Distributions For Federal Income Tax Purposes
Income Tax Contingency [Line Items]
Ordinary income (in dollars per share)			$ 0.520	$ 0.820	$ 0.870
Ordinary income			90.00%	77.00%	100.00%