Mortgage Loans, Construction Loan and Interest Rate Swaps (Details) $ in Thousands						1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 01, 2021 USD ($) loan building	Nov. 16, 2021 USD ($)	Aug. 05, 2021	May 07, 2021 USD ($)	Jan. 23, 2020 USD ($) ft² subsidiary building	Dec. 31, 2020 USD ($) derivative	Jun. 30, 2020 USD ($)	Mar. 31, 2022	Dec. 31, 2021 USD ($) item derivative	Dec. 31, 2020 USD ($) derivative
Long-Term Debt
Mortgage loans, net of debt issuance costs						$ 160,655			$ 169,818	$ 160,655
Interest rate (as a percent)							3.50%
Debt disclosures
Interest expense						602			6,877	7,294
Number of mortgage loans repaid | loan	2
Payment on secured debt						$ 417			$ 17,100	$ 7,948
Term of debt							10 years		1 year
Amortization period of debt							25 years
New mortgage							$ 5,100
Payment for termination of interest rate swap agreement									$ 66
Losses on early extinguishment of debt									(2,114)
Borrower deposited in escrow account									1
Escrow account balance									$ 300
Minimum Debt Service Coverage Ratio									1.25
Maximum Percentage Of Loan To Value									65.00%
Interest rate swap agreement
Debt disclosures
Number of interest rate swap derivatives | derivative						13			12	13
Notional amount of interest rate swap agreement						$ 97,868			$ 90,984	$ 97,868
Number of agreements containing credit risk related contingent features | item									0
Recognized net gains (losses) (included in other comprehensive loss), before taxes, on interest rate swap agreements						196			$ 4,945	(5,315)
Loss expected to be reclassified over next twelve months from accumulated other comprehensive loss to interest expense									(1,557)
Interest expense						182			2,082	1,246
Net fair value of interest rate swap agreements						8,766			3,807	8,766
Interest rate swap agreement | Other assets
Debt disclosures
Net fair value of interest rate swap agreements									188
Interest rate swap agreement | Other liabilities
Debt disclosures
Net fair value of interest rate swap agreements									3,995
LIBOR
Debt disclosures
Variable interest rate margin (as a percent)							2.56%
Nonrecourse mortgage loans
Long-Term Debt
Loans, prior to debt issuance costs						162,768			145,668	162,768
Debt issuance costs, net						(2,113)			(1,745)	(2,113)
Mortgage loans, net of debt issuance costs						$ 160,655			$ 143,923	$ 160,655
Weighted average interest rate						4.18%			3.76%	4.18%
Annual principal payment requirements under the terms of the nonrecourse mortgage loans
2022									$ 4,349
2023									4,535
2024									4,722
2025									19,932
2026									33,233
Debt disclosures
Aggregate book value of land and buildings pledged as collateral									164,736
Construction loan
Long-Term Debt
Loans, prior to debt issuance costs									26,273
Debt issuance costs, net									(378)
Mortgage loans, net of debt issuance costs									$ 25,895
Construction loan | LIBOR | Maximum
Debt disclosures
Variable interest rate margin (as a percent)									1.65%
Acquisition Credit Line | LIBOR
Debt disclosures
Variable interest rate margin (as a percent)			2.75%
4.39%, due January 2, 2025
Long-Term Debt
Loans, prior to debt issuance costs						$ 18,453			$ 17,824	$ 18,453
Interest rate (as a percent)						4.39%			4.39%	4.39%
4.17%, due May 1, 2026
Long-Term Debt
Loans, prior to debt issuance costs						$ 12,696			$ 12,291	$ 12,696
Interest rate (as a percent)						4.17%			4.17%	4.17%
3.79%, November 17, 2026
Long-Term Debt
Loans, prior to debt issuance costs						$ 23,911			$ 23,152	$ 23,911
Interest rate (as a percent)						3.79%			3.79%	3.79%
4.39%, due August 1, 2027
Long-Term Debt
Loans, prior to debt issuance costs						$ 9,750			$ 9,476	$ 9,750
Interest rate (as a percent)						4.39%			4.39%	4.39%
3.97%, due September 1, 2027
Long-Term Debt
Loans, prior to debt issuance costs						$ 11,419			$ 11,174	$ 11,419
Interest rate (as a percent)						3.97%			3.97%	3.97%
4.57%, due February 1, 2028
Long-Term Debt
Loans, prior to debt issuance costs						$ 17,601			$ 17,145	$ 17,601
Interest rate (as a percent)						4.57%			4.57%	4.57%
3.60%, due January 2, 2030
Long-Term Debt
Loans, prior to debt issuance costs						$ 6,350			$ 6,182	$ 6,350
Interest rate (as a percent)						3.60%			3.60%	3.60%
3.48% due February 1 2030
Long-Term Debt
Loans, prior to debt issuance costs						$ 14,682			$ 14,287	$ 14,682
Interest rate (as a percent)					3.48%	3.48%			3.48%	3.48%
Debt disclosures
Term of debt					10 years
Amortization period of debt					25 years
New mortgage					$ 15,000
Number of buildings used as collateral | building					2
Area of collateralized properties completed (in square feet) | ft²					254,000
Repayment of debt					$ 3,191
Number of subsidiaries which are party to the mortgage | subsidiary					2
3.50%, due July 1, 2030
Long-Term Debt
Loans, prior to debt issuance costs						$ 5,046			$ 4,914	$ 5,046
Interest rate (as a percent)						3.50%			3.50%	3.50%
4.33%, due August 1, 2030
Long-Term Debt
Loans, prior to debt issuance costs						$ 16,244			$ 15,867	$ 16,244
Interest rate (as a percent)						4.33%			4.33%	4.33%
4.51%, due April 1, 2034
Long-Term Debt
Loans, prior to debt issuance costs						$ 13,688			$ 13,356	$ 13,688
Interest rate (as a percent)						4.51%			4.51%	4.51%
4.72%, due October 3, 2022
Long-Term Debt
Loans, prior to debt issuance costs						$ 4,061				$ 4,061
Interest rate (as a percent)		4.72%				4.72%				4.72%
Debt disclosures
Payment on secured debt		$ 3,961
Debt extinguishment costs		15
Interest expense		$ 66
4.72%, due October 3, 2022 | LIBOR
Long-Term Debt
Interest rate (as a percent)		2.75%
5.09%, due July 1, 2029 GCD mortgage loan
Long-Term Debt
Loans, prior to debt issuance costs						$ 5,214				$ 5,214
Interest rate (as a percent)	5.09%					5.09%				5.09%
Debt disclosures
Payment on secured debt	$ 4,759
Debt extinguishment costs	$ 1,226
5.09%, due July 1, 2029 TD mortgage Loan
Long-Term Debt
Loans, prior to debt issuance costs						$ 3,653				$ 3,653
Interest rate (as a percent)	5.09%					5.09%				5.09%
Debt disclosures
Payment on secured debt	$ 3,335
Debt extinguishment costs	$ 873
Number of buildings mortgaged | building	2
JPM Construction Loan Two Thousand Twenty One [Member]
Debt disclosures
Term of debt				2 years
Extension term of debt				1 year
JPM Construction Loan Two Thousand Twenty One [Member] | Maximum
Debt disclosures
Loan amount				$ 28,400
Face amount as a percentage of total cost				67.50%
JPM Construction Loan Two Thousand Twenty One [Member] | LIBOR
Debt disclosures
Variable interest rate margin (as a percent)								1.40%
JPM Construction Loan Two Thousand Twenty One [Member] | LIBOR | Completion of Charlotte build to suit and commencement of rental payment
Debt disclosures
Variable interest rate margin (as a percent)				1.40%
JPM Construction Loan Two Thousand Twenty One [Member] | LIBOR | Maximum
Debt disclosures
Variable interest rate margin (as a percent)				1.65%