Accrued Expenses - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Accrued expenses
Accrued accounts payable	$ 4,251		$ 943
Compensation expense	2,870		2,380
Research and development fees	1,048		1,945
Lease liabilities	733	$ 442	0
Audit and tax fees	522		378
Other current liabilities	458		945
Accrued license obligations	62		2,523
Total	$ 9,944		$ 9,114

Accrued License Obligations

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- Definition

Accrued Research And Development Costs

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- Definition

Accrued Tax Audit And Legal Fees

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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