Notes Payable, Revolving Credit Facility, Interest and Amortization of Deferred Debt Costs - Scheduled Maturities of Debt, Including Scheduled Principal Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balloon Payments
October 1 through December 31, 2020	$ 0
2021	11,012
2022	161,002
2023	84,225
2024	66,164
2025	20,363
Thereafter	566,375
Principal amount	909,141
Scheduled Principal Amortization
October 1 through December 31, 2020	7,453
2021	30,323
2021	30,984
2022	31,447
2023	30,815
2024	27,823
Thereafter	117,532
Principal amount	276,377
Total
October 1 through December 31, 2020	7,453
2021	41,335
2022	191,986
2023	115,672
2024	96,979
2025	48,186
Thereafter	683,907
Principal amount	1,185,518	$ 1,100,000
Unamortized deferred debt costs	9,735	9,700
Net	1,175,783
Debt Instrument [Line Items]
Outstanding line of credit	123,778	86,371
Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding line of credit	$ 124,500	$ 87,500

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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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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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