Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Revenue	$ 1,386,520	$ 1,211,220	$ 1,143,492
Cost of Goods Sold	1,047,764	899,175	911,875
Gross Profit	338,756	312,045	231,617
Equity in Earnings of Unconsolidated Joint Venture	43,419	42,386	39,083
Corporate General and Administrative Expense	(41,205)	(33,940)	(37,193)
Legal Settlements	(45,098)
Other Non-Operating Income	3,728	2,139	2,328
Acquisition-Related Expense		(5,480)
Interest Expense, Net	(27,638)	(22,631)	(16,583)
Earnings before Income Taxes	271,962	294,519	219,252
Income Taxes	(15,330)	(96,300)	(66,660)
Net Earnings	$ 256,632	$ 198,219	$ 152,592
EARNINGS PER SHARE
Basic	$ 5.33	$ 4.14	$ 3.08
Diluted	$ 5.28	$ 4.10	$ 3.05
AVERAGE SHARES OUTSTANDING
Basic	48,141,226	47,931,518	49,471,157
Diluted	48,645,986	48,361,286	50,070,829
CASH DIVIDENDS PER SHARE	$ 0.40	$ 0.40	$ 0.40