Segment Reporting - Long-lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment reporting
Long-lived Assets	$ 114,304	$ 120,376	$ 126,090
US
Segment reporting
Long-lived Assets	80,081	86,345	92,509
Canada
Segment reporting
Long-lived Assets	3,235	3,841	6,972
Europe
Segment reporting
Long-lived Assets	25,907	26,130	22,883
Asia Pacific
Segment reporting
Long-lived Assets	$ 5,081	$ 4,060	$ 3,726