Earnings Per Share - Additional Information (Details)	Sep. 30, 2020
4.50% Cumulative Convertible Preferred Stock
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
5.00% (2005B)
Debt Instrument [Line Items]
Interest rate, stated percentage	5.00%
5.75% Cumulative Convertible Non-Voting Preferred Stock (Series A)
Debt Instrument [Line Items]
Interest rate, stated percentage	5.75%
5.75% Cumulative Non-Voting Convertible Preferred Stock
Debt Instrument [Line Items]
Interest rate, stated percentage	5.75%
Convertible debt | 5.5% Convertible Senior Notes due 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	5.50%