Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Earnings	$ 38,501	$ 36,335	$ 90,747	$ 89,635
Other Comprehensive (Loss) Income:
Foreign Currency Translation Adjustment	(535)	446	(1,012)	649
Total Other Comprehensive (Loss) Income	(535)	446	(1,012)	649
Comprehensive Income	$ 37,966	$ 36,781	$ 89,735	$ 90,284