Consolidated Statements of Earnings (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Income Statement [Abstract]
Net sales	$ 731,092	$ 827,637	$ 1,434,001	$ 1,683,496
Cost of goods sold	595,618	707,026	1,185,169	1,445,594
Gross margin	135,474	120,611	248,832	237,902
Selling, general and administrative expense	82,129	88,543	164,325	179,366
Impairment of long-lived assets	3,815	0	13,739	40,601
Restructuring and other expense (income), net	7,596	(50)	9,444	405
Incremental expenses related to Nikola gains	4,570	0	54,081	0
Operating income	37,364	32,118	7,243	17,530
Other income (expense):
Miscellaneous income, net	376	636	827	1,331
Interest expense	(7,548)	(7,315)	(15,138)	(16,795)
Equity in net income of unconsolidated affiliates	25,631	47,346	49,265	72,113
Gains (loss) on investment in Nikola	(143,780)	0	652,362	0
Loss on extinguishment of debt	0	0	0	(4,034)
Earnings (loss) before income taxes	(87,957)	72,785	694,559	70,145
Income tax expense (benefit)	(19,445)	15,863	144,333	15,678
Net earnings (loss)	(68,512)	56,922	550,226	54,467
Net earnings attributable to noncontrolling interests	5,532	4,836	7,595	7,157
Net earnings (loss) attributable to controlling interest	$ (74,044)	$ 52,086	$ 542,631	$ 47,310
Basic
Average common shares outstanding	52,988	55,059	53,532	55,150
Earnings (loss) per share attributable to controlling interest	$ (1.40)	$ 0.95	$ 10.14	$ 0.86
Diluted
Average common shares outstanding	52,988	56,072	54,439	56,205
Earnings (loss) per share attributable to controlling interest	$ (1.40)	$ 0.93	$ 9.97	$ 0.84
Common shares outstanding at end of period	52,754	55,094	52,754	55,094
Cash dividends declared per share	$ 0.25	$ 0.24	$ 0.50	$ 0.48