Preferred Stock (Details)											12 Months Ended			24 Months Ended
	Sep. 30, 2022 USD ($) shares	Sep. 27, 2022 USD ($) $ / shares shares	May 06, 2021 USD ($) $ / shares shares	Apr. 15, 2021 USD ($) shares	Mar. 23, 2021 USD ($) $ / shares shares	Sep. 23, 2019 USD ($) $ / shares shares	Aug. 19, 2019 USD ($) $ / shares shares	Jun. 27, 2019 USD ($) $ / shares shares	Apr. 12, 2019 USD ($) shares	Mar. 28, 2019 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2016 $ / shares	Dec. 31, 2016 $ / shares shares
Public Offering of Preferred Stock
Net proceeds											$ 137,459,000	$ 191,084,000
8% Preferred Stock
Public Offering of Preferred Stock
Redemption of 8% preferred stock (in shares) | shares				41,625
Redemption of 8% preferred stock				$ 41,600,000
Preferred stock, dividend rate (as a percent)			8.00%	8.00%
Final dividend for redemption of 8% preferred stock				$ 139,000
8% Preferred Stock | Private Placement
Public Offering of Preferred Stock
Shares issued (in shares) | shares														41,625
Preferred stock, dividend rate (as a percent)													8.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares													$ 1,000.00	$ 1,000.00
7% Series A Preferred Stock
Public Offering of Preferred Stock
Redemption of 8% preferred stock (in shares) | shares						874,000
Preferred stock, dividend rate (as a percent)						7.00%					7.00%	7.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares						$ 25					$ 25	$ 25
Redemption of preferred stock						$ 21,850,000
Brokerage fees						$ 0
7% Series A Preferred Stock | Public Offering
Public Offering of Preferred Stock
Shares issued (in shares) | shares									81,800	2,000,000
Preferred stock, dividend rate (as a percent)										7.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares										$ 25.00
Aggregate gross offering proceeds for the shares issued										$ 50,000,000.0
Net proceeds									$ 2,000,000.0	48,300,000
Offering costs										$ 1,700,000
Underwriting discounts									$ 41,000
7% Series A Preferred Stock | Private Placement
Public Offering of Preferred Stock
Shares issued (in shares) | shares								874,000
Preferred stock, dividend rate (as a percent)								7.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares								$ 25.00
Aggregate gross offering proceeds for the shares issued								$ 21,850,000
6% Series B Preferred Stock
Public Offering of Preferred Stock
Preferred stock, dividend rate (as a percent)											6.00%	6.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares											$ 1,000	$ 1,000
6% Series B Preferred Stock | Public Offering
Public Offering of Preferred Stock
Depositary shares issued (in shares) | shares							5,000,000
Depositary shares equivalent preferred stock interest per share							0.025
Preferred stock, dividend rate (as a percent)							6.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares							$ 1,000.00
Depositary share, preferred stock liquidation preference (in dollars per share) | $ / shares							$ 25.00
Aggregate gross offering proceeds for the shares issued							$ 125,000,000.0
Net proceeds							120,800,000
Underwriting discounts							$ 4,200,000
6% Series C Preferred Stock
Public Offering of Preferred Stock
Shares issued (in shares) | shares			46,181
Depositary shares issued (in shares) | shares			1,847,233
Depositary share price (in dollars per share) | $ / shares			$ 25
Preferred stock, dividend rate (as a percent)											6.00%	6.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares											$ 1,000	$ 1,000
Net proceeds			$ 46,200,000
Offering costs			$ 23,000
6% Series C Preferred Stock | Public Offering
Public Offering of Preferred Stock
Depositary shares issued (in shares) | shares					6,000,000
Depositary shares equivalent preferred stock interest per share					0.025
Preferred stock, dividend rate (as a percent)					6.00%
Preferred stock liquidation preference (in dollars per share) | $ / shares					$ 1,000.00
Depositary share, preferred stock liquidation preference (in dollars per share) | $ / shares					$ 25.00
Aggregate gross offering proceeds for the shares issued					$ 150,000,000.0
Net proceeds					144,900,000
Underwriting discounts					$ 5,100,000
8.25% Series D Preferred Stock
Public Offering of Preferred Stock
Preferred stock, dividend rate (as a percent)											8.25%
Preferred stock liquidation preference (in dollars per share) | $ / shares											$ 1,000
8.25% Series D Preferred Stock | Public Offering
Public Offering of Preferred Stock
Shares issued (in shares) | shares		5,200,000
Depositary shares equivalent preferred stock interest per share		0.025
Preferred stock, dividend rate (as a percent)		8.25%
Preferred stock liquidation preference (in dollars per share) | $ / shares		$ 1,000.00
Depositary share, preferred stock liquidation preference (in dollars per share) | $ / shares		$ 25.00
Aggregate gross offering proceeds for the shares issued		$ 130,000,000.0
Net proceeds		125,400,000
Underwriting discounts		$ 4,600,000
Series D Preferred Stock | Public Offering
Public Offering of Preferred Stock
Shares issued (in shares) | shares	500,000
Net proceeds	$ 12,100,000
Underwriting discounts	$ 400,000