Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
		Feb. 06, 2023	Mar. 31, 2023	Mar. 31, 2022	Mar. 21, 2023	Dec. 31, 2022	Jun. 13, 2018
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Shares Issued			13,420,421			9,420,421
Proceeds from Issuance of Preferred Stock and Preference Stock	[1]		$ 96,850	$ 506
Preferred Stock, Shares Authorized			100,000,000			100,000,000
Preferred Stock, Par or Stated Value Per Share			$ 0.001			$ 0.001
Common stock, shares authorized (in shares)			100,000,000			100,000,000
Common Stock, Par or Stated Value Per Share			$ 0.001			$ 0.001
Dividends declared (in usd per share)			$ 0.45	$ 0.45
Dividends paid			$ (33,981)	$ (29,105)
Common shares issued and outstanding upon conversion of all convertible securities (in shares)			68,001,009			64,628,148
Number of shares authorized to be repurchased (in shares)							1,550,000
Shares Issued As Payment of Incentive Fee, Shares			0	19,094
Preferred Stock, Shares Outstanding			13,420,421			9,420,421
Shares repurchased (in shares)			(1,061,000)	0
Average price per share (USD per share)			$ 11.38
Total cost			$ (12,072)
Stock Issued During Period, Shares, New Issues			4,433,861	2,185,000
Incentive Fee, Loss Carryforward			$ 45,300			$ 85,000
Stock Repurchase Program, Authorized Amount			$ 46,100		$ 50,000
Preferred ATM Program
Subsidiary, Sale of Stock [Line Items]
Maximum shares available to be issued under at the market program			100,000,000
Commissions and offering costs				$ 23
Stock Issued During Period, Shares, New Issues				20,421
Proceeds from issuance of shares, net				$ 500
Common ATM Program
Subsidiary, Sale of Stock [Line Items]
Maximum shares available to be issued under at the market program			10,000,000
Commissions and offering costs				$ 600
Stock Issued During Period, Shares, New Issues				2,185,000
Proceeds from issuance of shares, net				$ 38,500
Common ATM Programs
Subsidiary, Sale of Stock [Line Items]
Commissions and offering costs			$ 900
Stock Issued During Period, Shares, New Issues			4,433,861
Proceeds from issuance of shares, net			$ 60,500
2023 Common ATM Program
Subsidiary, Sale of Stock [Line Items]
Maximum shares available to be issued under at the market program			225,000,000
Series C Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Commissions and offering costs			$ 3,500
Proceeds from issuance of shares, net			$ 96,500
Series A Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage			6.75%
Preferred Stock, Par or Stated Value Per Share			$ 0.001
Preferred Stock, Liquidation Preference Per Share			$ 25.00
Preferred Stock Dividend Rate Variable Rate Spread			5.196%
Preferred Stock, Amount of Preferred Dividends in Arrears			$ 3,800	$ 2,500
Preferred Stock, Shares Outstanding			4,600,000			4,600,000
Series B Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage			6.25%
Preferred Stock, Par or Stated Value Per Share			$ 0.001
Preferred Stock, Liquidation Preference Per Share			$ 25.00
Preferred Stock Dividend Rate Variable Rate Spread			4.99%
Preferred Stock, Shares Outstanding			4,820,421			4,820,421
Series C Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage		8.625%
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Preferred Stock, Liquidation Preference Per Share		$ 25.00
Preferred Stock Dividend Rate Variable Rate Spread		5.13%
Preferred Stock, Shares Outstanding			4,000,000

[1] Net of discounts and commissions.