Stockholders' Equity - Cash Dividends Declared - Preferred Stock (Details) - $ / shares	Jul. 15, 2019	Apr. 15, 2019	Jan. 15, 2019	Oct. 15, 2018	Jul. 15, 2018	Apr. 15, 2018
Series B Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)		$ 0.484375	$ 0.484375	$ 0.484375	$ 0.484375	$ 0.484375
Series C Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)		0.4921875	0.4921875	0.4921875	0.4921875	0.4921875
Series D Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)		$ 0.50	$ 0.50	$ 0.50	$ 0.50	$ 0.50
Subsequent Event \| Series B Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)	$ 0.484375
Subsequent Event \| Series C Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)	0.4921875
Subsequent Event \| Series D Preferred Stock
Dividends Payable [Line Items]
Cash Dividend Per Share (in dollars per share)	$ 0.50