Note 7 - Leases (Details Textual) - USD ($) $ in Thousands		3 Months Ended
Jan. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Operating Lease Liabilities		$ (341)
Operating Lease, Cost		366	418
Short-term Lease, Cost		$ 13	$ 14
UNITED KINGDOM \| Previous Accounting Guidance [Member]
Lessee, Operating Lease, Term of Contract		15 years
Accounting Standards Update 2016-02 [Member]
Increase (Decrease) in Operating Lease Liabilities	$ 5,197
Increase (Decrease) in Operating Lease Right-of-Use Assets	$ 4,816

The amount of increase (decrease) in operating lease liabilities.

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- Definition

The amount of increase (decrease) in operating lease right of use assets.

+ References

No definition available.

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

+ References

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

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- Definition

Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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