Income taxes - Provision for Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
U.S. Federal	$ 0	$ 0	$ 0
U.S. State and Local	(61)	(38)	(6)
Foreign	(2,041)	(669)	(1,131)
Deferred:
U.S. Federal	0	0	(198)
U.S. State and Local	(8,812)	0	0
Foreign	(736)	736	0
Total tax benefit (expense)	$ (11,650)	$ 29	$ (1,335)

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

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