Debt - Scheduled Principal Repayments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2021	$ 416,614
2022	528,008
2023	415,506
2024	212,020
2025	65,325
Thereafter	132,581
Long-term debt and convertible notes payable	1,770,054	$ 1,717,928
Unamortized premium	548	651
Net unamortized debt issuance costs	(6,763)	(10,383)
Total Indebtedness	$ 1,763,839	$ 1,708,196

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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, after accumulated amortization, of debt premium.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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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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