Stockholders' Equity - Preferred Stock (Details) - $ / shares			1 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	May 31, 2016	Mar. 31, 2016
Series E Cumulative Redeemable Preferred Stock
Stockholders' equity
Number of shares of preferred stock sold (in shares)				4,600,000
Preferred stock, Cumulative Redeemable Preferred Stock, dividend rate (as a percent)	6.95%	6.95%		6.95%
Liquidation preference (in dollars per share)	$ 25.00	$ 25.00		$ 25.00
Redemption price (in dollars per share)				$ 25.00
Series F Cumulative Redeemable Preferred Stock
Stockholders' equity
Number of shares of preferred stock sold (in shares)			3,000,000
Preferred stock, Cumulative Redeemable Preferred Stock, dividend rate (as a percent)	6.45%	6.45%	6.45%
Liquidation preference (in dollars per share)	$ 25.00	$ 25.00	$ 25.00
Redemption price (in dollars per share)			$ 25.00