Shareholders' Equity - Schedule of Declared Distributions (Details) - Series D - $ / shares	Aug. 15, 2018	Jul. 30, 2018	Jul. 12, 2018	May 15, 2018	Apr. 27, 2018	Feb. 15, 2018	Jan. 30, 2018
Class of Stock [Line Items]
Dividend declared (in dollars per share)					$ 0.40625		$ 0.40625
Dividend paid (in dollars per share)				$ 0.40625		$ 0.40625
Scenario, Forecast
Class of Stock [Line Items]
Dividend paid (in dollars per share)	$ 0.40625
Subsequent event
Class of Stock [Line Items]
Dividend declared (in dollars per share)		$ 0.40625	$ 0.40625