Foreign Operations - Long-Lived Tangible Assets by Geographic Area (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Long-lived Assets from External Customers and Long-Lived Assets [Line Items]
Long-lived tangible assets	$ 93,424	$ 100,455
United States
Long-lived Assets from External Customers and Long-Lived Assets [Line Items]
Long-lived tangible assets	13,385	14,504
People's Republic of China (PRC)
Long-lived Assets from External Customers and Long-Lived Assets [Line Items]
Long-lived tangible assets	64,347	79,382
All other countries
Long-lived Assets from External Customers and Long-Lived Assets [Line Items]
Long-lived tangible assets	$ 15,692	$ 6,569