Summary of significant accounting policies - Adoption of ASU 2016-02 (Details) $ in Thousands	Jan. 01, 2019 USD ($) lease	Dec. 31, 2019 USD ($) lease
Adoption of New Accounting Standards
Operating lease right-of use asset	$ 321	$ 524
Operating lease liabilities		514
Carrying value of debt		$ 0
Incremental borrowing rate		8.00%
Charlotte, NC
Adoption of New Accounting Standards
Lease extended term	2 months
ASU 2016-02, Leases
Adoption of New Accounting Standards
Election of practical expedients package	true
Number of short-term operating leases \| lease		2
ASU 2016-02, Leases \| Charlotte, NC
Adoption of New Accounting Standards
Short-term lease commitment	true
Number of short-term operating leases \| lease	1
ASU 2016-02, Leases \| Adjustment
Adoption of New Accounting Standards
Operating lease right-of use asset	$ 300
Operating lease liabilities	$ 300

The number of lessee’s operating leases with original terms of 12 months or less.

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- Definition

Indicates (true false) whether practical expedients are elected for not reassessing whether any expired or existing contract is or contains lease, lease classification for expired or existing lease, and initial direct cost for any existing lease.

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

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- Definition

Amount of lessee's right to use underlying asset under operating lease.

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- Definition

Weighted average discount rate for operating lease calculated at point in time.

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- Definition

Indicates (true false) whether short-term lease expense does not reasonably reflect lessee's short-term lease commitment.

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