Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net earnings	$ 619,790	$ 490,383	$ 432,533
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments, net of tax of $13,364 in 2018, $16,761 in 2017 and $12,867 in 2016	(32,390)	30,434	(23,743)
Other comprehensive (loss) income	(32,390)	30,434	(23,743)
Comprehensive income	587,400	520,817	408,790
Less comprehensive income attributable to the noncontrolling interest	718	844	1,337
Comprehensive income attributable to shareholders	$ 586,682	$ 519,973	$ 407,453