Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net income	$ 12,762	$ 12,059
Other comprehensive income (loss):
Foreign currency translation adjustment	3,198	(5,898)
Minimum post retirement benefit plan adjustments	27	18
Other comprehensive income (loss)	3,225	(5,880)
Total comprehensive income	$ 15,987	$ 6,179