(13) Segments

CVR Energy's revenues are derived from two operating segments: the petroleum segment and the nitrogen fertilizer segment. The Company evaluates the performance of its segments based primarily on segment operating income and EBITDA. For the purposes of the operating segment disclosure, the company presents operating income as it is the most comparable measure to the amounts presented on the condensed consolidated statement of operations. The other segment reflects intercompany eliminations, corporate cash and cash equivalents, income tax activities and other corporate activities that are not allocated to the operating segments.

The following table summarizes certain operating results and capital expenditures information by segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
	(in millions)
Net sales
Petroleum	$	1,824		$	1,338		$	3,282		$	2,762
Nitrogen Fertilizer	93			98			173			183
Other	(3		)	(2		)	(4		)	(3		)
Total	$	1,914		$	1,434		$	3,451		$	2,942
Operating income (loss)
Petroleum	$	117		$	(7	)	$	214		$	59
Nitrogen Fertilizer	—			12			(4		)	18
Other	(6		)	(4		)	(9		)	(8		)
Total operating income	111			1			201			69
Interest expense, net	(27		)	(27		)	(53		)	(54		)
Gain on derivatives, net	10			—			70			12
Other income, net	2			—			3			0
Earnings before income taxes	$	96		$	(26	)	$	221		$	27
Depreciation and amortization
Petroleum	$	33		$	32		$	67		$	66
Nitrogen Fertilizer	20			20			37			35
Other	2			2			4			4
Total	$	55		$	54		$	108		$	105
Capital expenditures
Petroleum	$	16		$	28		$	32		$	48
Nitrogen Fertilizer	6			4			9			9
Other	—			1			1			1
Total	$	22		$	33		$	42		$	58

The following table summarizes total assets by segment:



	As of June 30, 2018		As of December 31, 2017
	(in millions)
Total assets
Petroleum	$	2,366	$	2,270
Nitrogen Fertilizer	1,200		1,234
Other	284		303
Total	$	3,850	$	3,807