Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		7 Months Ended	12 Months Ended			31 Months Ended
	Jan. 25, 2020	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Jan. 24, 2020	Feb. 28, 2019	Jun. 13, 2018	Dec. 31, 2017
Subsidiary, Sale of Stock [Line Items]
Preferred Stock, Shares Issued			4,600,000	4,600,000		4,600,000
Proceeds from Issuance of Preferred Stock and Preference Stock			$ 0	$ 111,378
Preferred Stock, Dividend Rate, Percentage			6.75%	6.75%
Preferred Stock, Shares Outstanding			4,600,000	4,600,000		4,600,000
Preferred Stock, Shares Authorized			100,000,000	100,000,000		100,000,000
Preferred Stock, Par or Stated Value Per Share			$ 0.001	$ 0.001		$ 0.001
Preferred Stock, Liquidation Preference Per Share			$ 25.00			$ 25.00
Preferred Stock, Amount of Preferred Dividends in Arrears			$ 1,300	$ 1,500
Preferred Stock Dividend Rate Variable Rate Spread			5.196%
Common stock, shares authorized (in shares)		100,000,000	100,000,000	100,000,000	100,000,000	100,000,000
Common shares			$ 0.001	$ 0.001		$ 0.001		$ 0.001
Common stock, shares outstanding		29,796,601	43,781,684	38,647,943	29,796,601	43,781,684				31,335,938
Dividends declared (in usd per share)			$ 1.26	$ 1.81	$ 1.64
Dividends paid			$ (65,026)	$ (54,312)	$ (50,736)
Common shares issued and outstanding upon conversion of all convertible securities (in shares)		30,529,972	44,442,631	39,371,584	30,529,972	44,442,631
Number of shares authorized to be repurchased (in shares)									1,550,000
Shares repurchased (in shares)		361,090	290,050	50,825	1,547,148	701,965
Average price per share (USD per share)		$ 15.34	$ 10.54	$ 15.39		$ 13.36
Total cost		$ (5,500)	$ (3,056)	$ (782)	$ (23,131)	$ (9,400)
Stock Issued During Period, Shares, New Issues	5,290,000		5,290,000	8,855,000
Proceeds from issuance of shares, net							$ 95,300
Stock issued during period, shares, conversion of units					3,334
Over-Allotment Option [Member]
Subsidiary, Sale of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	690,000
OP LTIP Unit [Member]
Subsidiary, Sale of Stock [Line Items]
Stock issued during period, shares, conversion of units			0	13,092
Operating Partnership Units [Member]
Subsidiary, Sale of Stock [Line Items]
Stock issued during period, shares, conversion of units			133,154	34,075