Debt - Scheduled Principal Repayments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2017 (Remainder)	$ 174,707
2018	88,308
2019	228,523
2020	573,807
2021	255,055
Thereafter	298,771
Long-term debt and convertible notes payable	1,619,171	$ 1,505,670
Unamortized fair market value of assumed debt	881	1,336
Net unamortized debt issuance costs	(17,205)	(18,288)
Total indebtedness	$ 1,602,847	$ 1,488,718

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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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