Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net earnings	$ 120,606	$ 107,949	$ 322,928	$ 321,435
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax of $4,128 and $202 for the three months ended September 30, 2017 and 2016 and $14,019 and $223 for the nine months ended September 30, 2017 and 2016	7,489	260	25,585	(457)
Other comprehensive income (loss)	7,489	260	25,585	(457)
Comprehensive income	128,095	108,209	348,513	320,978
Less comprehensive income attributable to the noncontrolling interest	285	260	503	1,167
Comprehensive income attributable to shareholders	$ 127,810	$ 107,949	$ 348,010	$ 319,811