Restructuring (Details) $ in Thousands	1 Months Ended	3 Months Ended				6 Months Ended	12 Months Ended
	May 31, 2017 employee	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) employee	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($)
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							$ 453	$ 1,656	$ 0	$ 0
Restructuring charge		$ 100	$ 200		$ 2,500			504	2,515	753
Payments for restructuring								(1,553)	(986)	(754)
Restructuring reversals								(202)		(6)
Restructuring foreign currency fluctuation								48	127	7
Restructuring reserve, ending balance		453		$ 1,656		$ 453		453	1,656	0
Employee Severance | Manufacturing Transition
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							147	0	0	0
Restructuring charge								504	0	0
Payments for restructuring								(357)	0	0
Restructuring reversals								0		0
Restructuring foreign currency fluctuation								0	0	0
Restructuring reserve, ending balance		147		0		147		147	0	0
Employee Severance | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							293	1,528	0	0
Restructuring charge								0	2,258	0
Payments for restructuring								(1,035)	(845)	0
Restructuring reversals								(244)		0
Restructuring foreign currency fluctuation								44	115	0
Restructuring reserve, ending balance		293		1,528		293		293	1,528	0
Employee Severance | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							0	0	0	0
Restructuring charge								0	0	558
Payments for restructuring								0	0	(559)
Restructuring reversals								0		(6)
Restructuring foreign currency fluctuation								0	0	7
Restructuring reserve, ending balance		0		0		0		0	0	0
Facility Closing | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							13	128	0	0
Restructuring charge								0	257	0
Payments for restructuring								(161)	(141)	0
Restructuring reversals								42		0
Restructuring foreign currency fluctuation								4	12	0
Restructuring reserve, ending balance		13		128		13		13	128	0
Facility Closing | 2016 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance							0	0	0	0
Restructuring charge								0	0	195
Payments for restructuring								0	0	(195)
Restructuring reversals								0		0
Restructuring foreign currency fluctuation								0	0	0
Restructuring reserve, ending balance		$ 0		0		$ 0		$ 0	$ 0	$ 0
UNITED STATES | 2016 Restructuring
Restructuring Cost and Reserve [Line Items]
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]
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
IoT Products & Services | Manufacturing Transition
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | employee						51
IoT Products & Services | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge				2,500
IoT Products & Services | Employee Severance | Manufacturing Transition
Restructuring Reserve [Roll Forward]
Restructuring charge						$ 500
IoT Products & Services | Employee Severance | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge				2,300
IoT Products & Services | Facility Closing | 2017 Restructuring
Restructuring Reserve [Roll Forward]
Restructuring charge				$ 200
IoT Products & Services | UNITED STATES | 2017 Restructuring
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | employee	10
IoT Products & Services | FRANCE | 2017 Restructuring
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | employee	8
Minimum | Forecast | IoT Products & Services | Manufacturing Transition
Restructuring Cost and Reserve [Line Items]
Effect on future earnings							3,000
Maximum | Forecast | IoT Products & Services | Manufacturing Transition
Restructuring Cost and Reserve [Line Items]
Effect on future earnings							$ 5,000