
15.	SEGMENT REPORTING

Our business is organized into four business units, each representing a reportable segment under ASC 280 Segment Reporting. The four segments are Driveline, Metal Forming, Powertrain and Casting. The results of each segment are regularly reviewed by the chief operating decision maker to assess the performance of the segment and make decisions regarding the allocation of resources to the segments. Refer to Note 2 - Revenue from Contracts with Customers for a description of our product offerings by segment.

We use Segment Adjusted EBITDA as the measure of earnings to assess the performance of each segment and determine the resources to be allocated to the segments. Segment Adjusted EBITDA is defined as EBITDA for our reportable segments excluding the impact of restructuring and acquisition-related costs, debt refinancing and redemption costs, gain on the sale of a business, and non-recurring items. The following tables represent information by reportable segment for the three months ended September 30, 2018 and 2017 (in millions):



	Three Months Ended September 30, 2018
	Driveline		Metal Forming		Powertrain		Casting		Total
Sales	$	1,068.0	$	382.2	$	285.4	$	219.1	$	1,954.7
Less: intersegment sales	0.3		108.8		3.3		25.3		137.7
Net external sales	$	1,067.7	$	273.4	$	282.1	$	193.8	$	1,817.0

Segment Adjusted EBITDA	$	159.3	$	66.9	$	34.3	$	14.5	$	275.0
	Three Months Ended September 30, 2017
	Driveline		Metal Forming		Powertrain		Casting		Total
Sales	$	1,007.9	$	368.2	$	260.9	$	226.6	$	1,863.6
Less: intersegment sales	0.2		106.8		3.8		28.4		139.2
Net external sales	$	1,007.7	$	261.4	$	257.1	$	198.2	$	1,724.4

Segment Adjusted EBITDA	$	181.5	$	70.7	$	36.8	$	8.8	$	297.8

The following tables represent information by reportable segment for the nine months ended September 30, 2018 and 2017:



	Nine Months Ended September 30, 2018
	Driveline		Metal Forming		Powertrain		Casting		Total
Sales	$	3,258.8	$	1,176.3	$	865.6	$	701.3	$	6,002.0
Less: intersegment sales	0.7		324.0		12.9		88.1		425.7
Net external sales	$	3,258.1	$	852.3	$	852.7	$	613.2	$	5,576.3

Segment Adjusted EBITDA	$	514.2	$	231.3	$	131.4	$	63.0	$	939.9
	Nine Months Ended September 30, 2017
	Driveline		Metal Forming		Powertrain		Casting		Total
Sales	$	3,028.7	$	887.5	$	544.5	$	452.2	$	4,912.9
Less: intersegment sales	1.1		315.1		6.0		58.6		380.8
Net external sales	$	3,027.6	$	572.4	$	538.5	$	393.6	$	4,532.1

Segment Adjusted EBITDA	$	513.7	$	170.5	$	88.7	$	34.3	$	807.2

The following table represents a reconciliation of Total Segment Adjusted EBITDA to consolidated income before income taxes for the three and nine months ended September 30, 2018 and 2017 (in millions):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Total Segment Adjusted EBITDA	$	275.0		$	297.8		$	939.9		$	807.2
Interest expense	(54.9		)	(57.5		)	(162.5		)	(139.9		)
Depreciation and amortization	(132.9		)	(122.6		)	(390.9		)	(303.4		)
Restructuring and acquisition-related costs	(11.7		)	(22.8		)	(66.8		)	(90.5		)
Pension settlement	—			(2.9		)	—			(2.9		)
Gain on sale of business	—			—			15.5			—
Gain on settlement of capital lease	—			—			15.6			—
Acquisition-related fair value inventory adjustment	—			—			—			(24.9		)
Impact of change in accounting principle	—			—			—			3.7
Debt refinancing and redemption costs	—			—			(14.6		)	(2.7		)
Income before income taxes	$	75.5		$	92.0		$	336.2		$	246.6