Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net earnings	$ 53,424	$ 126,950	$ 113,056
Other comprehensive earnings (loss):
Unrealized gain (loss) on marketable securities, net of tax	(7,436)	1,558	10,575
Other comprehensive earnings (loss), net of tax	(7,436)	1,558	10,575
Comprehensive earnings	$ 45,988	$ 128,508	$ 123,631