Segment Information

In the first quarter of 2018, the Company revised its reportable segments to consist of the following three segments: Clean Air, Ride Performance and Aftermarket. The new reportable segments, which are also the Company's operating segments, align with how the Chief Operating Decision Maker allocates resources and assesses performance against the Company’s key growth strategies. Costs related to other business activities, primarily corporate headquarter functions, are disclosed separately from the three operating segments as "Other." We evaluate segment performance based primarily on earnings before interest expense, income taxes, and noncontrolling interests. Products are transferred between segments and geographic areas on a basis intended to reflect as nearly as possible the “market value” of the products. Prior period segment information has been retrospectively revised to reflect our current segmentation. These changes also resulted in changes to the Company's reporting units. The Company allocated goodwill to its new reporting units in the first quarter of 2018, using a relative fair value approach, assessed potential goodwill impairment for all reporting units immediately before and immediately after the reallocation, and determined that no impairment existed.

The following table summarizes certain of the Company's segment information:



	Segments
	Clean Air		Ride Performance			Aftermarket		Total		Other			Reclass & Elims			Total
	(Millions)
At September 30, 2018 and for the Three Months Ended September 30, 2018
Revenues from external customers	$	1,602	$	461		$	309	$	2,372	$	—		$	—		$	2,372
Intersegment revenues	14		16			12		42		—			(42		)	—
EBIT, Earnings (loss) before interest expense, income taxes, and noncontrolling interests	104		(5		)	45		144		(40		)	—			104
Total assets	3,008		1,079			885		4,972		—			56			5,028
At September 30, 2017 and for the Three Months Ended September 30, 2017
Revenues from external customers	$	1,495	$	457		$	322	$	2,274	$	—		$	—		$	2,274
Intersegment revenues	11		18			8		37		—			(37		)	—
EBIT, Earnings (loss) before interest expense, income taxes, and noncontrolling interests	100		7			50		157		(23		)	—			134
Total assets	2,912		1,100			864		4,876		—			59			4,935
At September 30, 2018 and for the Nine Months Ended September 30, 2018
Revenues from external customers	$	5,052	$	1,480		$	951	$	7,483	$	—		$	—		$	7,483
Intersegment revenues	42		45			35		122		—			(122		)	—
EBIT, Earnings (loss) before interest expense, income taxes, and noncontrolling interests	328		8			130		466		(132		)	—			334
Total assets	3,008		1,079			885		4,972		—			56			5,028
At September 30, 2017 and for the Nine Months Ended September 30, 2017
Revenues from external customers	$	4,589	$	1,327		$	967	$	6,883	$	—		$	—		$	6,883
Intersegment revenues	53		46			29		128		—			(128		)	—
EBIT, Earnings (loss) before interest expense, income taxes, and noncontrolling interests	300		52			146		498		(216		)	—			282
Total assets	2,912		1,100			864		4,876		—			59			4,935