Income Taxes - Federal Income Tax Treatment of Common Dividends (Details) - Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Ordinary Income (A)	$ 0.7650	$ 0.6858	$ 0.6552
Unrecaptured Section 1250 Capital Gain	0.1074	0.1497	0.1627
Other Capital Gain	0.0460	0.0330	0.0648
Qualified Dividend	0.0016	0.0015	0
Distributions Per Common Share	$ 0.9200	$ 0.8700	$ 0.8827
Ordinary Income as a Percentage of Distributions	83.15%	78.83%	74.23%
Unrecaptured Section 1250 Gain as a Percentage of Distributions	11.68%	17.21%	18.43%
Capital Gain as a Percentage of Distributions	5.00%	3.79%	7.34%
Qualified Dividend as a Percentage Of Distributions	0.17%	0.17%	0.00%
Common Distributions Percentage	100.00%	100.00%	100.00%