Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net earnings	$ 163,067	$ 120,606	$ 440,213	$ 322,928
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of tax of $2,904 and $4,128 for the three months ended September 30, 2018 and 2017 and $12,563 and $14,019 for the nine months ended September 30, 2018 and 2017	(10,929)	7,489	(28,129)	25,585
Other comprehensive (loss) income	(10,929)	7,489	(28,129)	25,585
Comprehensive income	152,138	128,095	412,084	348,513
Less comprehensive (loss) income attributable to the noncontrolling interest	(167)	285	230	503
Comprehensive income attributable to shareholders	$ 152,305	$ 127,810	$ 411,854	$ 348,010