Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net earnings	$ 432,533	$ 459,497	$ 379,460
Other comprehensive loss, net of tax:
Foreign currency translation adjustments, net of tax of $12,687 in 2016, $23,801 in 2015 and $17,348 in 2014	(23,743)	(44,090)	(32,080)
Reclassification adjustments for foreign currency realized losses, net of tax of $61 in 2014	0	0	111
Other comprehensive loss	(23,743)	(44,090)	(31,969)
Comprehensive income	408,790	415,407	347,491
Less comprehensive income attributable to the noncontrolling interest	1,337	1,605	2,155
Comprehensive income attributable to shareholders	$ 407,453	$ 413,802	$ 345,336