Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
NET EARNINGS	$ 137,505	$ 22,665
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	(5)
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	138,255	25,644
Pension Plans [Member]
Other comprehensive income (loss), net of tax	726	2,951
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(215)	(931)
Post-Retirement Plans [Member]
Other comprehensive income (loss), net of tax	24	33
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	$ (7)	$ (10)