Issuances of Common Stock - Dividend Reinvestment and Stock Purchase Plan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Dividend Reinvestment and Stock Purchase Plan
Gross proceeds			$ 8,208	$ 6,922
DRSPP
Dividend Reinvestment and Stock Purchase Plan
Dividend Reinvestment and Stock Purchase Plan, authorized shares (in shares)	26,000,000		26,000,000
Shares remaining for future issuance (in shares)	11,378,949		11,378,949
Common stock | DRSPP
Dividend Reinvestment and Stock Purchase Plan
Shares of common stock issued (in shares)	41,613	34,604	124,430	113,421
Gross proceeds	$ 2,900	$ 2,100	$ 8,200	$ 6,900