Leases - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) factory	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Rent expense	$ 4,900	$ 4,200	$ 4,000
Liability related to rent escalations	1,100	1,200
Allowance for moving expenses and tenant improvements	1,800
Net book value of asset	$ 95,840	110,962
People's Republic of China (PRC)
Operating Leased Assets [Line Items]
Number of factories | factory	1
Net book value of asset	$ 76,400	$ 93,600
Yangzhou
Operating Leased Assets [Line Items]
Net book value of prepaid lease	$ 2,500
Prepaid lease assets, remaining amortization period	40 years
Yangzhou | Buildings on Prepaid Land
Operating Leased Assets [Line Items]
Net book value of asset	$ 18,200
Remaining depreciable period of asset	21 years
Property Subject to Rent Escalations | Minimum
Operating Leased Assets [Line Items]
Term of lease	48 months
Property Subject to Rent Escalations | Maximum
Operating Leased Assets [Line Items]
Term of lease	125 months