Subsequent Event (Details) - Netherlands Restructuring Plan - Subsequent Event $ in Millions	1 Months Ended
	Jul. 31, 2018 USD ($) employee
Subsequent Event [Line Items]
Expected savings amount	$ 3.0
Expected percentage of workforce reduction	20.00%
Minimum
Subsequent Event [Line Items]
Expected number of positions eliminated | employee	35
Restructuring and Related Cost, Expected Completion Period	6 months
Maximum
Subsequent Event [Line Items]
Expected number of positions eliminated | employee	40
Restructuring and Related Cost, Expected Completion Period	8 months
Employee Severance | Minimum
Subsequent Event [Line Items]
Expected costs to be incurred	$ 0.6
Employee Severance | Maximum
Subsequent Event [Line Items]
Expected costs to be incurred	$ 0.8