Debt - Scheduled Principal Repayments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2018 (Remainder)	$ 50,789
2019	207,882
2020	432,972
2021	181,484
2022	62,529
Thereafter	537,210
Long-term debt and convertible notes payable	1,472,866	$ 1,438,386
Unamortized fair market value of assumed debt	805	856
Net unamortized debt issuance costs	(12,417)	(14,833)
Total indebtedness	$ 1,461,254	$ 1,424,409

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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 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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