Commitments and Contingencies - Preferred Dividend Arrearages (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) $ / shares
Other Commitments [Line Items]
Cumulative amount of unpaid dividends on preferred stock | $	$ 20.5
Series B Preferred Stock
Other Commitments [Line Items]
Preferred stock annual dividend rate	$ 1.8436
Unpaid dividends per share on preferred stock	1.38
Series C Preferred Stock
Other Commitments [Line Items]
Preferred stock annual dividend rate	1.80
Unpaid dividends per share on preferred stock	1.35
Series D Preferred Stock
Other Commitments [Line Items]
Preferred stock annual dividend rate	1.7188
Unpaid dividends per share on preferred stock	$ 1.29