Operating segments are defined as components of an enterprise that engage in business activities that earn revenue, incur expenses, and prepare separate financial information that is evaluated regularly by our chief operating decision maker in order to allocate resources and assess performance.

We are a leading supplier of heavy construction materials and light building materials in the United States. Our primary products are commodities that are essential in commercial and residential construction; public construction projects; and projects to build, expand, and repair roads and highways. Demand for our products is generally cyclical and seasonal, depending on economic and geographic conditions. We distribute our products across many United States markets, which provides us with regional economic diversification. We also produce sand used in hydraulic fracturing as part of our Oil and Gas Proppants segment.

Our business is organized into three sectors within which there are five reportable business segments. The Heavy Materials sector includes the Cement and Concrete and Aggregates segments. The Light Materials sector includes the Gypsum Wallboard and Recycled Paperboard segments. The Oil and Gas Proppants segment produces frac sand used in oil and gas extraction.

Our operations are conducted in the U.S. and include the mining of limestone for the manufacture, production, distribution, and sale of portland cement (a basic construction material which is the essential binding ingredient in concrete); the grinding and sale of slag; the mining of gypsum for the manufacture and sale of gypsum wallboard; the manufacture and sale of recycled paperboard to the gypsum wallboard industry and other paperboard converters; the sale of readymix concrete; and the mining and sale of aggregates (crushed stone, sand, and gravel) and sand used in hydraulic fracturing (frac sand).

We operate eight modern cement plants (one of which is operated through a joint venture located in Buda, Texas), one slag grinding facility, and 29 cement distribution terminals. Our cement companies focus on the U.S. heartland and operate as an integrated network selling product primarily in California, Colorado, Illinois, Indiana, Iowa, Kentucky, Missouri, Nebraska, Nevada, Ohio, Oklahoma, and Texas. We operate 26 readymix concrete batch plants and five aggregates processing plants in markets that are complementary to our cement network. On April 17, 2017 we sold our Concrete and Aggregates companies in northern California. See Footnote (C) for more information about the sale.

We operate five gypsum wallboard plants and a recycled paperboard mill. We distribute gypsum wallboard and recycled paperboard throughout the continental U.S., with the exception of the Northeast.

Our Oil and Gas Proppants business owns two frac sand processing facilities, four frac sand drying facilities, and two frac sand trans-load locations. Frac sand is currently sold into shale deposits across the United States.

We account for intersegment sales at market prices. For segment reporting purposes only, we proportionately consolidate our 50% share of the Joint Venture Revenue and Operating Earnings, consistent with the way management reports the segments within the Company for making operating decisions and assessing performance.

The following tables below sets forth certain financial information relating to our operations by segment. We do not allocate interest or taxes at the segment level, only at the consolidated company level.

	For the Years Ended March 31,
	2020			2019			2018
	(dollars in thousands)
Revenue -
Cement	$	752,002		$	656,759		$	651,750
Concrete and Aggregates		182,775			140,173			157,013
Gypsum Wallboard		508,145			532,712			491,779
Paperboard		159,963			167,656			181,742
Oil and Gas Proppants		46,781			82,987			98,244
		1,649,666			1,580,287			1,580,528
Less: Intersegment Revenue		(85,316	)		(82,553	)		(88,124	)
Less: Joint Venture Revenue		(113,536	)		(104,493	)		(105,884	)
	$	1,450,814		$	1,393,241		$	1,386,520

	For the Years Ended March 31,
	2020		2019		2018
	(dollars in thousands)
Intersegment Revenue -
Cement	$	21,499	$	14,408	$	16,442
Concrete and Aggregates		1,502		1,422		1,335
Paperboard		62,315		66,723		70,347
	$	85,316	$	82,553	$	88,124
Cement Sales Volume (M tons) -
Wholly Owned		4,975		4,441		4,453
Joint Venture		956		899		912
		5,931		5,340		5,365

	For the Years Ended March 31,
	2020				2019			2018
				(dollars in thousands)
Operating Earnings -
Cement	$	181,330			$	164,782		$	179,151
Concrete and Aggregates		17,558				12,866			17,854
Gypsum Wallboard		154,614				180,831			158,551
Paperboard		34,979				35,349			32,758
Oil and Gas Proppants		(14,634	)			(28,695	)		(6,139	)
Sub-Total		373,847				365,133			382,175
Corporate General and Administrative Expense		(65,410	)			(37,371	)		(41,205	)
Impairment Losses		(224,267	)			(220,265	)		—
Litigation Settlements and Losses		—				(1,800	)		(45,098	)
Other Non-Operating Income		(25	)			2,412			3,728
Earnings Before Interest and Income Taxes		84,145				108,109			299,600
Interest Expense, net		(38,421	)			(28,374	)		(27,638	)
Earnings Before Income Taxes	$	45,724			$	79,735		$	271,962
Cement Operating Earnings -
Wholly Owned	$	138,745			$	126,217		$	135,732
Joint Ventures		42,585				38,565			43,419
	$	181,330			$	164,782		$	179,151
Capital Expenditures -
Cement	$	44,776			$	76,504		$	45,088
Concrete and Aggregates		11,898				6,649			4,977
Gypsum Wallboard		12,771				10,724			19,382
Paperboard		62,528				16,603			5,177
Oil and Gas Proppants		146				52,286			56,872
Other, net		—				6,107			461
	$	132,119			$	168,873		$	131,957
Depreciation, Depletion, and Amortization -
Cement	$	59,081			$	52,802		$	50,891
Concrete and Aggregates		11,142				8,176			7,931
Gypsum Wallboard		20,320				20,020			18,179
Paperboard		8,945				8,541			8,694
Oil and Gas Proppants		11,310				31,328			26,872
Corporate and Other		2,720				1,668			1,448
	$	113,518			$	122,535		$	114,015

	As of March 31,
	2020		2019		2018
	(dollars in thousands)
Identifiable Assets
Cement	$	1,980,306	$	1,289,468	$	1,247,504
Concrete and Aggregates		136,041		95,084		104,851
Gypsum Wallboard		375,946		372,206		386,041
Paperboard		183,288		138,614		123,819
Oil and Gas Proppants		14,294		236,357		444,826
Other, net		271,145		37,434		60,962
	$	2,961,020	$	2,169,163	$	2,368,003

Segment Operating Earnings, including the proportionately consolidated 50% interest in the revenue and expenses of the Joint Venture, represent Revenue less direct operating expenses, segment Depreciation, and segment Selling, General, and Administrative expenses. Segment Operating Earnings don’t include certain non-recurring losses, such as impairment and legal settlements. We account for intersegment sales at market prices. Corporate assets consist primarily of cash and cash equivalents, general office assets, and miscellaneous other assets.

The basis used to disclose Identifiable Assets; Capital Expenditures; and Depreciation, Depletion, and Amortization conforms with the equity method, and is similar to how we disclose these accounts in our Consolidated Balance Sheets and Consolidated Statements of Earnings.