Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
NET EARNINGS	$ 105,328	$ 33,103	$ 101,392	$ 73,615
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(1)	22	1,473	(117)
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	108,325	33,855	112,156	75,686
Pension Plans [Member]
Other comprehensive income (loss), net of tax	2,965	687	9,189	2,061
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(917)	(200)	(2,457)	(600)
Post-Retirement Plans [Member]
Other comprehensive income (loss), net of tax	33	43	102	127
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(10)	(12)	(27)	(38)
Retained Earnings [Member]
NET EARNINGS		$ 33,103
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	$ 105,328		$ 101,392	$ 73,615