Investments in Unconsolidated Joint Ventures - Balance sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Real estate, net	$ 289,300	$ 289,728	$ 302,609	$ 295,631	$ 285,429	$ 275,674
Cash and cash equivalents	1,381	4,310	917	2,169	5,034	6,515	$ 9,196
Restricted cash	14,232	20,535	11,732	7,626	6,694	9,554	$ 9,474
Prepaid expenses and other assets, net	5,007	4,126	3,555	2,934	3,343	2,703
Intangible assets, net	8,247	8,432	8,617	8,802	8,987	9,172
Total assets	338,086	346,581	347,049	337,121	330,800	325,618
LIABILITIES
Accounts payable and accrued expenses	19,876	17,864	18,457	17,458	14,368	15,896
Total liabilities	285,209	291,163	295,297	284,480	273,424	261,240
STOCKHOLDERS' EQUITY
Accumulated deficit	(33,323)	(30,785)	(26,341)	(24,989)	(19,957)	(13,033)
Accumulated other comprehensive loss	(1,224)	(1,343)	(1,803)	(1,922)	(2,040)	(2,159)
Total liabilities and stockholders' equity	338,086	346,581	347,049	337,121	330,800	325,618
Our investments in unconsolidated joint ventures	18,517	17,938	$ 18,056	$ 18,318	$ 18,814	$ 19,379
Unconsolidated Joint Ventures
ASSETS
Real estate, net	163,303	164,143
Cash and cash equivalents	1,393	1,244
Restricted cash	929	891
Tenant and other receivables, net	229	225
Prepaid expenses and other assets, net	1,055	315
Intangible assets, net	20,944	21,527
Total assets	187,853	188,345
LIABILITIES
Mortgages payable, net	111,326	112,934
Accounts payable and accrued expenses	1,821	1,849
Total liabilities	113,147	114,783
STOCKHOLDERS' EQUITY
Members' equity	87,539	87,654
Accumulated deficit	(12,833)	(14,092)
Total members' equity	74,706	73,562
Total liabilities and stockholders' equity	187,853	188,345
Our investments in unconsolidated joint ventures	$ 18,517	$ 17,938