CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 40,345	$ 38,793	$ 37,284
Other comprehensive income (loss), net of tax:
Change in post-employment benefits	732	(151)	147
Other comprehensive income (loss)	732	(151)	147
Comprehensive income	$ 41,077	$ 38,642	$ 37,431