Consolidated Statements of Changes in Equity (Unaudited) - USD ($)	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total Greystone Stockholders' Equity [Member]	Non-controlling Interest [Member]	Total
Balance at May. 31, 2019	$ 5	$ 2,836	$ 53,790,764	$ (51,108,677)	$ 2,684,928	$ 1,126,271	$ 3,811,199
Balance, shares at May. 31, 2019	50,000	28,361,201
Cash distributions						(52,200)	(52,200)
Preferred dividends				(112,363)	(112,363)		(112,363)
Net income				554,613	554,613	64,686	619,299
Balance at Aug. 31, 2019	$ 5	$ 2,836	53,790,764	(50,666,427)	3,127,178	1,138,757	4,265,935
Balance, shares at Aug. 31, 2019	50,000	28,361,201
Balance at May. 31, 2019	$ 5	$ 2,836	53,790,764	(51,108,677)	2,684,928	1,126,271	3,811,199
Balance, shares at May. 31, 2019	50,000	28,361,201
Net income							1,091,984
Balance at Nov. 30, 2019	$ 5	$ 2,836	53,790,764	(50,361,999)	3,431,606	1,134,777	4,566,383
Balance, shares at Nov. 30, 2019	50,000	28,361,201
Balance at Aug. 31, 2019	$ 5	$ 2,836	53,790,764	(50,666,427)	3,127,178	1,138,757	4,265,935
Balance, shares at Aug. 31, 2019	50,000	28,361,201
Cash distributions						(69,600)	(69,600)
Preferred dividends				(102,637)	(102,637)		(215,000)
Net income				407,065	407,065	65,620	472,685
Balance at Nov. 30, 2019	$ 5	$ 2,836	53,790,764	(50,361,999)	3,431,606	1,134,777	4,566,383
Balance, shares at Nov. 30, 2019	50,000	28,361,201
Balance at May. 31, 2020	$ 5	$ 2,836	53,790,764	(46,807,092)	6,986,513	1,173,020	8,159,533
Balance, shares at May. 31, 2020	50,000	28,361,201
Cash distributions						(52,200)	(52,200)
Preferred dividends				(81,918)	(81,918)		(81,918)
Net income				942,119	942,119	67,039	1,009,158
Balance at Aug. 31, 2020	$ 5	$ 2,836	53,790,764	(45,946,891)	7,846,714	1,187,859	9,034,573
Balance, shares at Aug. 31, 2020	50,000	28,361,201
Balance at May. 31, 2020	$ 5	$ 2,836	53,790,764	(46,807,092)	6,986,513	1,173,020	8,159,533
Balance, shares at May. 31, 2020	50,000	28,361,201
Net income							2,032,231
Balance at Nov. 30, 2020	$ 5	$ 2,836	53,790,764	(45,073,711)	8,719,894	1,203,634	9,923,528
Balance, shares at Nov. 30, 2020	50,000	28,361,201
Balance at Aug. 31, 2020	$ 5	$ 2,836	53,790,764	(45,946,891)	7,846,714	1,187,859	9,034,573
Balance, shares at Aug. 31, 2020	50,000	28,361,201
Cash distributions						(52,200)	(52,200)
Preferred dividends				(81,918)	(81,918)		(81,918)
Net income				955,098	955,098	67,975	1,023,073
Balance at Nov. 30, 2020	$ 5	$ 2,836	$ 53,790,764	$ (45,073,711)	$ 8,719,894	$ 1,203,634	$ 9,923,528
Balance, shares at Nov. 30, 2020	50,000	28,361,201