Revision of Previously Issued Financial Statements - Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pro forma Balance Sheet:
Contract assets	$ 7,202	$ 5,240
Total current assets	207,178	209,801
Contract assets - non-current	1,877	3,355
Total assets	375,203	382,542
Short-term income taxes payable	2,618	7,410
Total current liabilities	75,304	73,812
Total liabilities	117,863	120,248
Retained earnings	173,731	179,440
Total stockholders' equity	257,340	262,294	$ 251,639	$ 237,930
Total liabilities and stockholders' equity	$ 375,203	382,542
As Previously Reported
Pro forma Balance Sheet:
Contract assets		7,058
Total current assets		211,619
Contract assets - non-current		3,565
Total assets		384,570
Short-term income taxes payable		7,711
Total current liabilities		74,113
Total liabilities		120,549
Retained earnings		181,167
Total stockholders' equity		264,021
Total liabilities and stockholders' equity		384,570
Adjustment
Pro forma Balance Sheet:
Contract assets		(1,818)
Total current assets		(1,818)
Contract assets - non-current		(210)
Total assets		(2,028)
Short-term income taxes payable		(301)
Total current liabilities		(301)
Total liabilities		(301)
Retained earnings		(1,727)
Total stockholders' equity		(1,727)
Total liabilities and stockholders' equity		$ (2,028)