Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Revenue, Major Customer [Line Items]

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

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

	Year Ended December 31
	2016				2015				2014
$ in millions	$		%(4)		$		%(4)		$		%(4)
U.S. Government(1)	$	20,573	84	%	$	19,458	83	%	$	20,085	84	%
International(2)	3,205		13	%	3,339		14	%	3,045		13	%
Other Customers(3)	730		3	%	729		3	%	849		3	%
Total Sales	$	24,508			$	23,526			$	23,979

⁽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.

⁽³⁾  Sales to Other Customers include sales to U.S. state and local governments and commercial sales in the U.S.

⁽⁴⁾  Percentage of total sales.

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	2016		2015		2014
Operating Income	$	494	$	580	$	664
Net Earnings(1)	321		377		432
Diluted earnings per share(1)	1.78		1.97		2.04

⁽¹⁾  Based on statutory tax rates

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	2016			2015
Land and land improvements	Up to 40(1)	$	415		$	381
Buildings and improvements	Up to 45	1,798			1,618
Machinery and other equipment	Up to 20	4,711			4,610
Capitalized software costs	3-5	439			406
Leasehold improvements	Length of Lease(2)	1,056			898
Property, plant and equipment, at cost		8,419			7,913
Accumulated depreciation		(4,831		)	(4,849		)
Property, plant and equipment, net		$	3,588		$	3,064

⁽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	2016			2015
Unamortized benefit plan costs, net of tax benefit of $3,439 in 2016 and $3,350 in 2015	$	(5,416	)	$	(5,241	)
Cumulative translation adjustment	(132		)	(82		)
Net unrealized gain on marketable securities and cash flow hedges, net of tax	2			3
Total accumulated other comprehensive loss	$	(5,546	)	$	(5,320	)