SEGMENT INFORMATION

We have five operating segments, Aerospace, Combat Systems, Information Technology, Mission Systems and Marine Systems. We organize our segments in accordance with the nature of products and services offered. We measure each segment’s profitability based on operating earnings. As a result, we do not allocate net interest, other income and expense items, and income taxes to our segments.

Summary financial information for each of our segments follows:



	Revenue				Operating Earnings					Revenue from U.S. Government
Three Months Ended	September 30, 2018		October 1, 2017		September 30, 2018			October 1, 2017		September 30, 2018		October 1, 2017
Aerospace	$	2,031	$	1,995	$	376		$	381	$	48	$	48
Combat Systems	1,523		1,500		241			247		765		754
Information Technology	2,307		1,068		157			101		2,245		1,011
Mission Systems	1,230		1,086		179			152		994		892
Marine Systems	2,003		1,931		169			179		1,932		1,921
Corporate	—		—		13			3		—		—
Total	$	9,094	$	7,580	$	1,135		$	1,063	$	5,984	$	4,626
Nine Months Ended
Aerospace	$	5,751	$	6,147	$	1,108		$	1,241	$	213	$	138
Combat Systems	4,497		4,201		701			677		2,188		2,217
Information Technology	5,887		3,178		414			278		5,693		2,985
Mission Systems	3,475		3,226		478			451		2,769		2,591
Marine Systems	6,205		5,944		548			518		5,983		5,872
Corporate	—		—		(18		)	11		—		—
Total	$	25,815	$	22,696	$	3,231		$	3,176	$	16,846	$	13,803

Corporate operating results have two primary components: pension and other post-retirement benefit income, and stock option expense. ASU 2017-07 requires the non-service cost components of pension and other post-retirement benefit cost (e.g., interest cost) to be reported in other income (expense) in the Consolidated Statement of Earnings. In our defense segments, as described in Note N, pension and other post-retirement benefit costs are allocable contract costs. For these segments, we report the offset for the non-service cost components in Corporate operating results. Corporate operating results in the first nine months of 2018 also included one-time charges of approximately $45 associated with the costs to complete the CSRA acquisition.

The following is additional summary financial information for each of our segments:



	Capital Expenditures				Depreciation and Amortization
Nine Months Ended	September 30, 2018		October 1, 2017		September 30, 2018		October 1, 2017
Aerospace	$	142	$	87	$	112	$	112
Combat Systems	47		49		64		63
Information Technology	36		9		229		23
Mission Systems	39		34		49		43
Marine Systems	147		71		83		79
Corporate	36		23		5		6
Total	$	447	$	273	$	542	$	326

Identifiable assets for each of our segments follows:



	September 30, 2018		December 31, 2017
Aerospace	$	11,444	$	10,126
Combat Systems	10,584		9,846
Information Technology	14,674		3,021
Mission Systems	6,093		5,856
Marine Systems	2,945		2,906
Corporate*	1,223		3,291
Total	$	46,963	$	35,046

* Corporate identifiable assets are primarily cash and equivalents.