Income tax (expense) benefit (Tables)

12 Months Ended

Dec. 31, 2017

Income tax (expense) benefit

Schedule of loss before income taxes attributable to domestic and international operations

	Year ended December 31
(in thousands)	2015			2016			2017
Domestic	$	(46,300	)	$	(54,509	)	$	(66,109	)
Foreign		(1,109	)		(1,053	)		(6,892	)
Loss before income taxes	$	(47,409	)	$	(55,562	)	$	(73,001	)

Schedule of income tax (expense) benefit

	Year ended December 31
(in thousands)	2015			2016			2017
Current tax
Domestic	$	(3	)	$	(4	)	$	—
Foreign		(172	)		(118	)		55
Deferred tax
Domestic		—			—			—
Foreign		620			794			(1,410	)
Total income tax (expense) benefit	$	445		$	672		$	(1,355	)

Schedule of effective income tax rate reconciliation

	Year ended December 31
(% of pre-tax income)	2015			2016			2017
Statutory income tax rate		25.0	%		25.0	%		12.5	%
Non-deductible expenses		(0.1	)		(0.2	)		(0.8	)
Income not subject to tax		1.9			2.8			0.9
Impairment		—			—			1.4
Tax credits		—			0.4			0.2
Foreign rate differential		(5.0	)		(2.5	)		21.0
Other		0.2			0.2			(1.4	)
Valuation allowance		(21.1	)		(24.5	)		(35.6	)
Effective income tax rate		0.9	%		1.2	%		(1.8	)%

Summary of the components of deferred income tax balances

(in thousands)	2016			2017
Deferred tax assets:
Net operating loss carryforwards	$	54,220		$	70,871
Tax loss on liquidation of subsidiary		—			7,846
Equity compensation		1,025			1,450
Non-deductible reserves		409			57
Total deferred tax assets		55,654			80,224
Valuation allowance		(54,114	)		(80,087	)
Net deferred tax assets		1,540			137
Deferred tax liabilities:
Financial liabilities		95			80
Property, plant and equipment		35			57
Total deferred tax liability		130			137
Deferred tax, net	$	1,410		$	—

Summary of changes in the deferred tax valuation allowance

	Year ended December 31,
(in thousands)	2015			2016			2017
Balance at beginning of year	$	(30,507	)	$	(40,487	)	$	(54,114	)
Tax benefit		(9,980	)		(13,627	)		(25,973	)
Balance at end of year	$	(40,487	)	$	(54,114	)	$	(80,087	)

Summary of carryforwards of net operating losses

        The following table summarizes carryforwards of net operating losses as of December 31, 2017.

(in thousands)	Amount		Expiration
Ireland	$	27,490	Indefinite
Austria	$	268,285	Indefinite
United States	$	200	2037