Asset sale (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition services agreement receivable (Note 5)		$ 11,999	$ 12,817
Transition services agreement payables (Note 5)		11,769	11,222
Assets held for sale		2,971	0
Gain within operating income		(200)	$ 2,193	$ 0
Other current liabilities | Indemnification agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent liability		$ 6,800
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale				13,900
Reclassification from assets held-for-sale	$ 3,400
Assets sold	12,800
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Inventories
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, other				13,100
Assets sold	12,100
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Property, plant and equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, other				$ 800
Assets sold	700
APAT OE | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received pursuant to asset purchase agreement	25,000
Proceeds from post-closing transaction services fees under transition services agreement	1,400
Disposal group consideration adjustment	21,600
Consideration adjustment for potential indemnification claims	$ 10,000