CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net earnings (loss)	$ 72	$ 128	$ 222	$ (161)
Other comprehensive income (loss):
Foreign currency translation adjustments	17	11	(25)	25
Changes in unamortized actuarial loss, net of tax expense of $8, $9, $24 and $120	23	29	67	373
Changes in unamortized net prior service credit, net of tax expense of $0, $0, $0 and $0	1	(1)	2	(1)
Total other comprehensive income	41	39	44	397
Total comprehensive income	$ 113	$ 167	$ 266	$ 236