Acquired Intangible Assets (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 30, 2019	Dec. 31, 2018
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		$ 123,542		$ 123,542			$ 98,871
Less accumulated amortization	[1]	(55,313)		(55,313)			(51,391)
Net acquired intangible assets		68,229		68,229			47,480
Amortization of acquired intangible assets [Abstract]
Amortization expense		2,100	$ 1,900	3,900	$ 3,800
Estimated amortization expense, remainder of 2019		4,100		4,100
Estimated amortization expense in year 2020		8,200		8,200
Estimated amortization expense in year 2021		6,800		6,800
Estimated amortization expense in year 2022		5,200		5,200
Estimated amortization expense in years 2023 through 2034		38,700		38,700
Customer Relationships [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		111,604		111,604			87,195
Trademarks [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		6,980		6,980			6,800
Intangible assets acquired [Abstract]
Amount of acquired indefinite-lived intangible assets		5,200		5,200
Non-compete Agreements [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		3,275		3,275			3,193
Patents [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		723		723			723
Supply Agreements [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		800		800			800
Leaseholds [Member]
Indefinite Lived Intangible Assets [Abstract]
Total acquired intangible assets		$ 160		$ 160			$ 160
Pollak business of Stoneridge, Inc. [Member]
Other Intangible Assets [Abstract]
Intangible assets						$ 24,650
Estimated useful life of intangible assets				15 years
Pollak business of Stoneridge, Inc. [Member] | OE/OES [Member]
Other Intangible Assets [Abstract]
Estimated useful life of intangible assets				10 years
Pollak business of Stoneridge, Inc. [Member] | Customer Relationships [Member]
Other Intangible Assets [Abstract]
Intangible assets						7,200
Estimated useful life of intangible assets				15 years
Pollak business of Stoneridge, Inc. [Member] | Customer Relationships [Member] | OE/OES [Member]
Other Intangible Assets [Abstract]
Intangible assets						17,200
Estimated useful life of intangible assets				10 years
Pollak business of Stoneridge, Inc. [Member] | Trademarks [Member]
Other Intangible Assets [Abstract]
Intangible assets						200
Estimated useful life of intangible assets				10 years
Pollak business of Stoneridge, Inc. [Member] | Non-compete Agreements [Member]
Other Intangible Assets [Abstract]
Intangible assets						$ 100
Estimated useful life of intangible assets				5 years

[1] Applies to all intangible assets, except for trademarks and trade names totaling $5.2 million, which have indefinite useful lives and, as such, are not being amortized.