Stockholders' Equity (Dividends Declared) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Dividends declared	$ 456.1	$ 240.2	$ 161.4
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 28.0	$ 28.0	$ 28.0
Dividends declared, per share amount (USD per share)	$ 70.00	$ 70.00	$ 70.00
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 18.0	$ 36.0	$ 36.0
Dividends declared, per share amount (USD per share)	$ 30.00	$ 60.00	$ 60.00
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 44.6	$ 44.6	$ 44.6
Dividends declared, per share amount (USD per share)	$ 59.52	$ 59.52	$ 59.52
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 27.8	$ 27.8	$ 27.8
Dividends declared, per share amount (USD per share)	$ 4,625	$ 4,625	$ 4,625
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 25.0	$ 25.0	$ 25.0
Dividends declared, per share amount (USD per share)	$ 5,000	$ 5,000	$ 5,000
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 134.4	$ 78.8
Dividends declared, per share amount (USD per share)	$ 5,375	$ 3,150.35
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 97.2
Dividends declared, per share amount (USD per share)	$ 3,888.89
Series I Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 63.2
Dividends declared, per share amount (USD per share)	$ 2,811.11
Series J Preferred Stock [Member]
Class of Stock [Line Items]
Dividends declared	$ 17.9
Dividends declared, per share amount (USD per share)	$ 29.80