Common Stock and Related Matters - Dividends Declared And Or Paid (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Dividends Payable [Line Items]
Accrued preferred dividends payable date		May 14, 2019
Dividends Declared per Share of Common Stock		$ 0.91	$ 0.91
Dividend Declared, Q1 2019 [Member]
Dividends Payable [Line Items]
Accrued preferred dividends payable date		May 15, 2019
Total Common Dividends Declared		$ 215.2
Amount of Common Dividends Paid or To Be Paid		211.5
Accrued Dividends	[1]	$ 3.7
Dividends Declared per Share of Common Stock		$ 0.91000
Dividend Declared, Q4 2018 [Member]
Dividends Payable [Line Items]
Accrued preferred dividends payable date		Feb. 15, 2019
Total Common Dividends Declared		$ 215.2
Amount of Common Dividends Paid or To Be Paid		211.2
Accrued Dividends	[1]	$ 4.0
Dividends Declared per Share of Common Stock		$ 0.91000

[1] Represents accrued dividends on restricted stock and restricted stock units that are payable upon vesting.