Notes Payable, Revolving Credit Facility, Interest and Amortization of Deferred Debt Costs - Scheduled Maturities of Debt, Including Scheduled Principal Amortization (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Balloon Payments
April 1 through December 31, 2021	$ 4,975
2022	140,502
2023	84,225
2024	66,164
2025	20,363
2026	134,088
Thereafter	437,162
Principal amount	887,479
Scheduled Principal Amortization
April 1 through December 31, 2021	22,838
2022	31,016
2022	31,481
2023	30,857
2024	27,860
2025	24,333
Thereafter	92,253
Principal amount	260,638
Total
April 1 through December 31, 2021	27,813
2022	171,518
2023	115,706
2024	97,021
2025	48,223
2026	158,421
Thereafter	529,415
Principal amount	1,148,117	$ 1,200,000
Unamortized deferred debt costs	8,934	9,300
Net	1,139,183
Debt Instrument [Line Items]
Outstanding line of credit	103,548	103,913
Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding line of credit	$ 104,000	$ 104,500

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

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