Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net earnings	$ 2,002	$ 5,302	$ 3,605
Adjustments to reconcile net earnings to net cash provided by operating activities
Depreciation and amortization	1,195	1,215	1,026
Stock-based compensation	158	149	138
Deferred income taxes	3,432	(152)	(445)
Severance charges	0	99	102
Gain on property sale	(198)	0	0
Gain on divestiture of IS&GS business	(73)	(1,242)	0
Gain on step acquisition of AWE	0	(104)	0
Changes in assets and liabilities
Receivables, net	(401)	(811)	(256)
Inventories, net	183	(46)	(398)
Accounts payable	(189)	(188)	(160)
Customer advances and amounts in excess of costs incurred	(24)	3	(32)
Postretirement benefit plans	1,316	1,028	1,068
Income taxes	(1,210)	146	(48)
Other, net	285	(210)	501
Net cash provided by operating activities	6,476	5,189	5,101
Investing activities
Capital expenditures	(1,177)	(1,063)	(939)
Acquisitions of businesses and investments in affiliates	0	0	(9,003)
Other, net	30	78	208
Net cash used for investing activities	(1,147)	(985)	(9,734)
Financing activities
Repurchases of common stock	(2,001)	(2,096)	(3,071)
Dividends paid	(2,163)	(2,048)	(1,932)
Special cash payment from divestiture of IS&GS business	0	1,800	0
Proceeds from stock option exercises	71	106	174
Repayments of long-term debt	0	(952)	0
Proceeds from the issuance of long-term debt	0	0	9,101
Proceeds from borrowings under revolving credit facilities	0	0	6,000
Repayments of borrowings under revolving credit facilities	0	0	(6,000)
Other, net	(212)	(267)	5
Net cash (used for) provided by financing activities	(4,305)	(3,457)	4,277
Net change in cash and cash equivalents	1,024	747	(356)
Cash and cash equivalents at beginning of year	1,837	1,090	1,446
Cash and cash equivalents at end of year	$ 2,861	$ 1,837	$ 1,090