Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net earnings	$ 2,015	$ 2,200	$ 1,990
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization	475	456	467
Stock-based compensation	94	93	99
Excess tax benefits from stock-based compensation	0	0	(103)
Deferred income taxes	603	36	572
Changes in assets and liabilities:
Accounts receivable, net	(677)	(461)	(30)
Inventoried costs, net	36	(15)	(80)
Prepaid expenses and other assets	(81)	(110)	43
Accounts payable and other liabilities	539	198	(632)
Income taxes payable, net	(157)	148	135
Retiree benefits	(191)	393	(263)
Other, net	(43)	(125)	(36)
Net cash provided by operating activities	2,613	2,813	2,162
Investing activities
Capital expenditures	(928)	(920)	(471)
Other investing activities, net	39	115	40
Net cash used in investing activities	(889)	(805)	(431)
Financing activities
Common stock repurchases	(393)	(1,547)	(3,182)
Net proceeds from issuance of long-term debt	8,245	749	600
Payments of long-term debt	0	(321)	0
Net (payments to) proceeds from credit facilities	(13)	135	0
Cash dividends paid	(689)	(640)	(603)
Payments of employee taxes withheld from share-based awards	(92)	(153)	(186)
Other financing activities, net	(98)	(9)	96
Net cash provided by (used in) financing activities	6,960	(1,786)	(3,275)
Increase (decrease) in cash and cash equivalents	8,684	222	(1,544)
Cash and cash equivalents, beginning of year	2,541	2,319	3,863
Cash and cash equivalents, end of year	$ 11,225	$ 2,541	$ 2,319