Business Segment, Geographic and Major Customer Information - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues from External Customers and Long-Lived Assets
Revenue	$ 8,880	$ 34,692	$ 28,296	$ 77,949
U.S.
Revenues from External Customers and Long-Lived Assets
Revenue	6,936	31,114	22,711	69,990
Other countries
Revenues from External Customers and Long-Lived Assets
Revenue	$ 1,944	$ 3,578	$ 5,585	$ 7,959