Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands													1 Months Ended							3 Months Ended	12 Months Ended			99 Months Ended	111 Months Ended
	Jan. 03, 2022	Oct. 12, 2021	Oct. 06, 2021	Oct. 04, 2021	May 11, 2021	Oct. 01, 2020	Feb. 26, 2020	Jan. 09, 2020	Oct. 30, 2019	Mar. 01, 2018	Apr. 01, 2017	Feb. 17, 2017	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Apr. 30, 2013	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2021	May 31, 2021	Sep. 30, 2020	Sep. 15, 2020	Dec. 31, 2018
Class of Stock [Line Items]
Stock dividends (in shares)						0.01349								0.014655	0.014655	0.014655	0.01349	0.01349			0.08871
Weighted-average price per share (in usd per share)							$ 17.50		$ 17.50												$ 0			$ 20.60	$ 20.60
Stock repurchase, value							$ 8,800	$ 1,700	$ 7,800
Repurchase price per share, percentage of estimated per-share NAV																					100.00%
Number of shares repurchased (in shares)							505,101		446,830												0			4,896,620	4,896,620
DRIP, period of notice to alter agreement												10 days
Common stock issued through distribution reinvestment plan (in shares)																						900,000	1,500,000
Proceeds from common stock issued through distribution reinvestment plan																						$ 14,600	$ 27,200
Number of securities called by share purchase right (in shares)																						1		1
Issuance of preferred stock, net (in shares)																					0
Distributions declared per share (in usd per share)						$ 0.85				$ 0.85	$ 1.45								$ 1.70			$ 0.42	$ 0.83
Preferred stock, quarterly dividend rate (in usd per share)																					0.460938
Subsequent Event
Class of Stock [Line Items]
Stock dividends (in shares)	0.014655												0.014655
Public Stock Offering
Class of Stock [Line Items]
Preferred stock, liquidation preference (in usd per share)			$ 25.00
Preferred stock, number of shares issued in public offering			3,630,000
Consideration received on transaction, gross			$ 90,800
Issuance of preferred stock, net			$ 86,800
Preferred Stock Equity Line
Class of Stock [Line Items]
Sale of stock, net proceeds																					$ 300
Authorized preferred stock offering, value																												$ 15,000
Maximum shares per preferred stock offering (in shares)																												3,500
Issuance of preferred stock, net (in shares)																					15,000
Proceeds from issuance of preferred stock																					$ 400
Stock issuance costs																					$ 1,200				$ 1,200
APIC, stock issuance costs																				$ 30
Public Offering
Class of Stock [Line Items]
Preferred stock, number of shares issued in public offering					2,352,144
Sale of stock, net proceeds					$ 56,000
Discount on offering					$ 2,900
Over-Allotment Option
Class of Stock [Line Items]
Preferred stock, number of shares issued in public offering		430,000			152,144
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)																					4,740,000	4,740,000		4,740,000	4,740,000
Preferred stock, additional shares authorized (in shares)																											600,000
Preferred stock, shares issued (in shares)																					3,977,144	1,610,000		1,610,000	3,977,144
Preferred stock, dividend rate, percentage																					7.375%	7.375%
Preferred stock, par value (in usd per share)																					$ 0.01	$ 0.01		$ 0.01	$ 0.01
Preferred stock, shares outstanding (in shares)																					3,977,144	1,610,000		1,610,000	3,977,144
Preferred stock, dividend rate (in usd per share)																					$ 1.84375
Preferred stock, liquidation preference (in usd per share)																					$ 25.00				$ 25.00
Issuance of preferred stock, net																					$ 56,265	$ (59)	$ 37,617
Series A Preferred Stock | Public Stock Offering
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)																							1,610,000			2,530,000
Preferred stock, liquidation preference (in usd per share)																					$ 25.00				$ 25.00
Series A Preferred Stock | Delisting
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage																					9.375%
Preferred stock, dividend rate (in usd per share)																					$ 2.34375
Increase in preferred stock, dividend rate, percentage																					2.00%
Series A Preferred Stock | Maximum
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)																							50,000,000
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)																					3,680,000	0		0	3,680,000
Preferred stock, shares issued (in shares)																					3,630,000	0		0	3,630,000
Preferred stock, dividend rate, percentage			7.125%	7.125%																	7.125%
Preferred stock, par value (in usd per share)				$ 0.01																	$ 0.01				$ 0.01
Preferred stock, shares outstanding (in shares)																					3,630,000	0		0	3,630,000
Preferred stock, dividend rate (in usd per share)																					$ 1.78125
Preferred stock, liquidation preference (in usd per share)																					$ 25.00				$ 25.00
Issuance of preferred stock, net																					$ 86,819
Preferred stock, quarterly dividend rate (in usd per share)																					0.445313
Series B Preferred Stock | Public Stock Offering
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)				3,680,000
Preferred stock, liquidation preference (in usd per share)																					$ 25.00				$ 25.00
Series B Preferred Stock | Delisting
Class of Stock [Line Items]
Preferred stock, dividend rate, percentage																					9.125%
Preferred stock, dividend rate (in usd per share)																					$ 2.28125
Increase in preferred stock, dividend rate, percentage																					2.00%
Tender Offer
Class of Stock [Line Items]
Shares authorized for repurchase (in shares)								200,000
Weighted-average price per share (in usd per share)								$ 8.50
Common Stock
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)																					99,281,754	93,775,746	92,356,664	93,775,746	99,281,754				91,963,532
Common stock issued through distribution reinvestment plan (in shares)																						875,986	1,481,395
Non-controlling Interests
Class of Stock [Line Items]
Preferred units, issued (in shares)																				100,000
Preferred unit issuance value																				$ 2,600