Distributions Paid and Payable - Distributions to Common Stockholders (Details) - $ / shares	1 Months Ended							3 Months Ended
	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Jan. 31, 2020	Mar. 31, 2019	Feb. 28, 2019	Jan. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Distributions Paid and Payable
Distributions paid per common share (in dollars per share)		$ 0.2325	$ 0.2325	$ 0.2275	$ 0.2255	$ 0.2255	$ 0.2210	$ 0.6925	$ 0.6720
Distributions payable (in dollars per share)		$ 0.233						$ 0.233
Subsequent event
Distributions Paid and Payable
Distributions paid per common share (in dollars per share)	$ 0.233