Revenue - Contract Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Capitalized Contract Cost [Line Items]
Amortization of capitalized costs	$ 14,078	$ 14,988
Capitalized costs, net	9,117	8,445
Tooling [Member]
Capitalized Contract Cost [Line Items]
Capitalized costs, net	5,908	6,155
Design Costs [Member]
Capitalized Contract Cost [Line Items]
Capitalized costs, net	3,209	2,285
Other Capitalized Contract Cost [Member]
Capitalized Contract Cost [Line Items]
Capitalized costs, net	$ 0	$ 5