Income taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income (Loss) before Income Taxes

The provision for income taxes is based upon the income (loss) before income taxes as follows (in thousands): 

	Years Ended December 31,
	2018			2017			2016
U.S. operations	$	(43,384	)	$	(52,725	)	$	(10,217	)
Non-U.S. operations	1,076			301			13,609
	$	(42,308	)	$	(52,424	)	$	3,392

Components of Provision for Income Taxes

The components of the provision for income taxes consisted of the following (in thousands): 

	Years Ended December 31,
	2018			2017			2016
Current
Federal	$	(49	)	$	(144	)	$	(127	)
State	36			3			(13		)
Foreign	(1,634		)	363			(3,925		)
	(1,647		)	222			(4,065		)
Deferred
Federal	42			4			(24		)
State	—			—			—
Foreign	276			(1,135		)	492
Total provision	$	(1,329	)	$	(909	)	$	(3,597	)

Difference in Provision for Income Taxes from Amount Obtained by Applying U.S. Federal Statutory Rate

The provision for income taxes differs from the amount obtained by applying the U.S. federal statutory tax rate as follows (in thousands, except percentages): 

	Years Ended December 31,
	2018			2017			2016
Federal statutory rate	21		%	35		%	35		%
Tax at federal statutory rate	$	8,869		$	18,354		$	(1,185	)
State taxes, net of federal benefit	36			2			(8		)
Mandatory repatriation/Section 956	—			(5,718		)	(19		)
Nondeductible expenses	(371		)	(67		)	(727		)
Stock-based compensation	(1,079		)	(314		)	(877		)
Change in valuation allowance	(10,094		)	16,273			(1,455		)
Research and development	914			851			1,175
Foreign rate differences	(697		)	(2,819		)	(1,215		)
Foreign tax credit	49			144			127
Change in prior year deferred balances	1,653			(28,262		)	920
Other	(609		)	647			(333		)
Total provision for income taxes from continuing operations	$	(1,329	)	$	(909	)	$	(3,597	)

Components of Deferred Income Tax Assets and Liabilities

Deferred income tax assets and liabilities comprise the following (in thousands): 

	December 31,
	2018			2017
Deferred Tax Assets:
Net operating loss carryforwards	$	56,828		$	44,912
Federal and state credits	28,328			26,170
Reserves, accruals and other	11,265			9,698
Fixed assets and intangibles	2,398			1,259
Total deferred tax assets	98,819			82,039
Valuation allowance	(92,891		)	(76,101		)
Total deferred tax assets, net of valuation allowance	5,928			5,938
Less deferred tax liabilities:
Acquired intangibles	(313		)	(2,054		)
Property, plant and equipment	(4,754		)	(3,338		)
Net deferred tax assets	$	861		$	546
Reported as:
Long term deferred tax assets, included within other long-term assets	$	861		$	652
Long term deferred income tax liabilities, included within noncurrent liabilities	—			(106		)
Net deferred tax assets	$	861		$	546

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 

Balance at December 31, 2015	$	20,686
Gross increases for tax positions of current year	2,920
Balance at December 31, 2016	23,606
Gross increases for tax positions of current year	1,933
Balance at December 31, 2017	25,539
Gross increases for tax positions of current year	657
Balance at December 31, 2018	$	26,196