Common Stock - Narrative (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 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	353,330	621,032	427,766	736,269
Sales Agency Agreement [Member]
Class Of Stock [Line Items]
Shares issued under sales agency agreements	300,000		300,000