Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Change in Accounting Estimate [Table Text Block]

The following table presents the effect of aggregate net EAC adjustments:

	Year Ended December 31
$ in millions, except per share data	2017		2016		2015
Operating income	$	363	$	494	$	580
Net earnings(1)	236		321		377
Diluted earnings per share(1)	1.34		1.78		1.97

⁽¹⁾  Based on statutory tax rates in effect for each year presented.

Revenue, Major Customer [Line Items]

Schedule of Revenue by Major Customers [Table Text Block]

Sales by Customer Category - The following table presents sales by customer category:

	Year Ended December 31
	2017				2016				2015
$ in millions	$		%		$		%		$		%
U.S. Government(1)	$	21,837	85	%	$	20,573	84	%	$	19,458	83	%
International(2)	3,302		13	%	3,205		13	%	3,339		14	%
Other Customers	664		2	%	730		3	%	729		3	%
Total Sales	$	25,803			$	24,508			$	23,526

⁽¹⁾  Sales to the U.S. Government include sales from contracts for which we are the prime contractor, as well as those for which we are a subcontractor and the ultimate customer is the U.S. Government. Each of the company’s segments derives substantial revenue from the U.S. Government.

⁽²⁾  International sales include sales from contracts for which we are the prime contractor, as well as those for which we are a subcontractor and the ultimate customer is an international customer. These sales include foreign military sales contracted through the U.S. Government, direct sales with governments outside the U.S. and commercial sales outside the U.S.

Property, Plant and Equipment

Major classes of property, plant and equipment and their useful lives are as follows:

		December 31
Useful life in years, $ in millions	Useful Life	2017			2016
Land and land improvements	Up to 40(1)	$	420		$	415
Buildings and improvements	Up to 40	1,834			1,798
Machinery and other equipment	Up to 20	5,105			4,711
Capitalized software costs	3-5	537			439
Leasehold improvements	Length of Lease(2)	1,395			1,056
Property, plant and equipment, at cost		9,291			8,419
Accumulated depreciation		(5,066		)	(4,831		)
Property, plant and equipment, net		$	4,225		$	3,588

⁽¹⁾  Land is not a depreciable asset.

⁽²⁾  Leasehold improvements are depreciated over the shorter of the useful life of the asset or the length of the lease.

Accumulated Other Comprehensive Loss

The components of accumulated other comprehensive loss are as follows:

	December 31
$ in millions	2017			2016
Unamortized benefit plan costs, net of tax benefit of $3,056 for 2017 and $3,439 for 2016	$	(4,586	)	$	(5,416	)
Cumulative translation adjustment	(136		)	(132		)
Net unrealized gain on marketable securities and cash flow hedges, net of tax	4			2
Total accumulated other comprehensive loss	$	(4,718	)	$	(5,546	)

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

The following table includes selected financial information that has been recast to reflect the adoption of Topic 606:

	Year Ended December 31
$ in millions, except per share amounts	2017		2016
Sales	$	26,004	$	24,706
Operating income	3,246		3,125
Net earnings	1,995		2,156
Basic earnings per share	$	11.44	$	12.05
Diluted earnings per share	11.36		11.94