Acquisition - Purchase price allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Oct. 06, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 337,028		$ 83,834
Triage Business
Business Acquisition [Line Items]
Prepaid expenses and other current assets		$ 796
Assets held for sale		146,540
Inventories		52,205
Property, plant and equipment		10,608
Intangible assets		184,900
Goodwill		245,531
Other non-current assets		182
Total assets acquired		640,762
Other current liabilities		(509)
Total net assets and liabilities acquired		$ 640,253