Debt - Future Scheduled Principal Payments of Debt Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2019 (remaining nine months)	$ 5,684
2020	9,536
2021	21,962
2022	106,954
2023	142,545
2024	296,658
Thereafter	15,908
Total debt before unamortized debt issue costs	599,247	$ 585,055
Unamortized mortgage debt issue costs	(1,679)	(1,773)
Total debt outstanding	$ 597,568	$ 583,282

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

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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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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