Consolidated Statement of Shareholders' Equity (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Dividends on common stock per share	$ 0.28	$ 0.24	$ 0.21
8% Preferred Stock | Preferred stock
Preferred stock, dividend rate (as a percent)	8.00%
Dividends on preferred stock per share	$ 80.00
Final dividend for redemption of preferred stock per share	$ 3.33
7% Series A Preferred Stock
Preferred stock, dividend rate (as a percent)	7.00%	7.00%
7% Series A Preferred Stock | Preferred stock
Preferred stock, dividend rate (as a percent)	7.00%
Dividends on preferred stock per share	$ 1.75
6% Series B Preferred Stock
Preferred stock, dividend rate (as a percent)	6.00%	6.00%
6% Series B Preferred Stock | Preferred stock
Preferred stock, dividend rate (as a percent)	6.00%
Dividends on preferred stock per share	$ 60.00
6% Series C Preferred Stock
Preferred stock, dividend rate (as a percent)	6.00%	6.00%
6% Series C Preferred Stock | Preferred stock
Preferred stock, dividend rate (as a percent)	6.00%
Dividends on preferred stock per share	$ 60.00
6% Series C Preferred Stock | Public Offering | Preferred stock
Offering expenses on issuance of stock	$ 5,100,000
6% Series C Preferred Stock | Private Placement | Preferred stock
Preferred stock, dividend rate (as a percent)	6.00%
Offering expenses on issuance of stock	$ 23,000
8.25% Series D Preferred Stock
Preferred stock, dividend rate (as a percent)	8.25%
8.25% Series D Preferred Stock | Preferred stock
Preferred stock, dividend rate (as a percent)	8.25%
Dividends on preferred stock per share	$ 82.50
8.25% Series D Preferred Stock | Public Offering | Preferred stock
Offering expenses on issuance of stock	$ 5,000,000.0