Financing Activity - Timing of Principal Payments and Terms of Mortgage Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Total
Carrying value of mortgage notes payable	$ 899,753	$ 1,047,906
Mortgage Loan
Total
Less: Unamortized debt issuance costs	1,800	$ 3,100
Mortgage Loan \| Consolidated Properties
Principal Amortization
2020	16,266
2021	17,862
2022	13,463
2023	6,584
2024	6,405
2025 and thereafter	4,406
Total principal payments	64,986
Balloon Payments
2020	27,161
2021	188,785
2022	355,988
2023	53,299
2024	0
2025 and thereafter	211,346
Total principal payments	836,579
Total
2020	43,427
2021	206,647
2022	369,451
2023	59,883
2024	6,405
2025 and thereafter	215,752
Total principal payments	901,565
Less: Unamortized debt issuance costs	1,812
Carrying value of mortgage notes payable	$ 899,753

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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