CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE EARNINGS (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net earnings	$ 131,435	$ 172,247
Foreign currency translation adjustments [Abstract]
Foreign currency translation gains	52,308	39,897
Reclassification of foreign currency translation losses to earnings	0	3,875
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	0	(3,875)
Total foreign currency translation adjustment	52,308	43,772
Pension and other postretirement benefit plans [Abstract]
Amortization of actuarial losses included in net periodic pension cost	1,939	1,338
Amortization of prior service cost included in net periodic pension cost	743	702
Total pension and other postretirement benefit plans	2,682	2,040
Changes in fair value of cash flow hedges [Abstract]
Unrealized net gains arising during period	1,362	78
Net gains reclassified into earnings	(253)	(217)
Total cash flow hedges	1,109	(139)
Other comprehensive income loss other adjustment, net of tax	0	337
Other comprehensive earnings	56,099	46,010
Comprehensive earnings	$ 187,534	$ 218,257