Common Stock - Narrative (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Common Stock [Member]
Class Of Stock [Line Items]
Number of shares authorized to issue by regulatory authority	3,900,000		3,900,000
Shares issued under sales agency agreements	1,100,545	821,196	1,528,311	1,557,465
Sales Agency Agreement [Member]
Class Of Stock [Line Items]
Shares issued under sales agency agreements	1,100,000		1,400,000
Common stock shares authorized to issue	2,500,000		2,500,000