Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities
Net earnings	$ 739	$ 650
Adjustments to reconcile to net cash used in operating activities:
Depreciation and amortization	122	104
Stock-based compensation	19	17
Deferred income taxes	(55)	(9)
Changes in assets and liabilities:
Accounts receivable, net	(187)	(317)
Unbilled receivables, net	(404)	(665)
Inventoried costs, net	(37)	(27)
Prepaid expenses and other assets	13	(53)
Accounts payable and other liabilities	(590)	(357)
Income taxes payable	197	152
Retiree benefits	(56)	86
Other, net	2	(20)
Net cash used in operating activities	(237)	(439)
Investing activities
Capital expenditures	(305)	(216)
Other, net	(2)	2
Net cash used in investing activities	(307)	(214)
Financing activities
Common stock repurchases	0	(229)
Cash dividends paid	(198)	(166)
Payments of employee taxes withheld from share-based awards	(79)	(90)
Net (payments to) proceeds from credit facilities	(14)	0
Other, net	(21)	0
Net cash used in financing activities	(312)	(485)
Decrease in cash and cash equivalents	(856)	(1,138)
Cash and cash equivalents, beginning of year	11,225	2,541
Cash and cash equivalents, end of period	$ 10,369	$ 1,403