Restructuring (Details) $ in Thousands	3 Months Ended			12 Months Ended
	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($) employee	Sep. 30, 2015 USD ($) employee
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 0	$ 0	$ 0	$ 0
Restructuring charge	$ 2,500	$ 100	700	2,515	753	412
Payments for restructuring				(986)	(754)	(403)
Restructuring reversals					(6)	(9)
Restructuring foreign currency fluctuation				127	7
Restructuring reserve, ending balance				1,656	0	0
Employee Severance | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	0	0	0
Restructuring charge				2,258	0	0
Payments for restructuring				(845)	0	0
Restructuring reversals					0	0
Restructuring foreign currency fluctuation				115	0
Restructuring reserve, ending balance				1,528	0	0
Employee Severance | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	0	0	0
Restructuring charge				0	558	0
Payments for restructuring				0	(559)	0
Restructuring reversals					(6)	0
Restructuring foreign currency fluctuation				0	7
Restructuring reserve, ending balance				0	0	0
Employee Severance | 2015 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	0	0	0
Restructuring charge				0	0	412
Payments for restructuring				0	0	(403)
Restructuring reversals					0	(9)
Restructuring foreign currency fluctuation				0	0
Restructuring reserve, ending balance				0	0	0
Facility Closing | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0	0	0	0
Restructuring charge				257	0	0
Payments for restructuring				(141)	0	0
Restructuring reversals					0	0
Restructuring foreign currency fluctuation				12	0
Restructuring reserve, ending balance				128	0	0
Facility Closing | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 0	0	0	0
Restructuring charge				0	195	0
Payments for restructuring				0	(195)	0
Restructuring reversals					0	0
Restructuring foreign currency fluctuation				0	0
Restructuring reserve, ending balance				$ 0	$ 0	$ 0
FRANCE | 2017 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee				8
Restructuring Reserve [Roll Forward]
Restructuring charge				$ 2,500
FRANCE | Employee Severance | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge				2,300
FRANCE | Facility Closing | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge				$ 200
UNITED STATES | 2017 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee				10
UNITED STATES | 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee					5
UNITED STATES | Employee Severance | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge					$ 100
GERMANY | 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee					10
Restructuring Reserve [Roll Forward]
Restructuring charge					$ 700
GERMANY | Employee Severance | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge					500
GERMANY | Facility Closing | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge					$ 200
INDIA | 2015 Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated | employee						38
INDIA | Employee Severance | 2015 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge						$ 400