CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings (loss)	$ 99	$ 255	$ (62)	$ 841
Other comprehensive income (loss):
Foreign currency translation adjustments	(6)	15	19	(16)
Changes in unamortized actuarial loss, net of tax expense of $8, $12, $128, and $94	25	38	398	291
Changes in unamortized net prior service credit, net of tax benefit of $0, $0, $0 and $1	0	(2)	(1)	(3)
Total other comprehensive income	19	51	416	272
Total comprehensive income	$ 118	$ 306	$ 354	$ 1,113