Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Income Statement [Abstract]
Interest income	$ 283,152	$ 276,499	$ 566,420	$ 556,083
Interest expense	(173,596)	(174,422)	(348,373)	(354,398)
Net interest income	109,556	102,077	218,047	201,685
Benefit (provision) for credit losses	3,400	(1,638)	(603)	(1,964)
Net interest income after benefit (provision) for credit losses	112,956	100,439	217,444	199,721
Non-interest income:
Fee and other income	4,831	6,332	8,772	9,848
Derivative gains (losses)	46,086	81,287	(126,077)	141,563
Investment securities gains (losses)	(4,344)	(1,361)	(6,569)	3,298
Total non-interest income	46,573	86,258	(123,874)	154,709
Non-interest expense:
Salaries and employee benefits	(12,380)	(14,011)	(25,690)	(27,144)
Other general and administrative expenses	(10,715)	(10,125)	(21,615)	(19,655)
Losses on early extinguishment of debt	(118)	(1,455)	(118)	(1,455)
Other non-interest expense	(313)	(323)	(569)	(655)
Total non-interest expense	(23,526)	(25,914)	(47,992)	(48,909)
Income before income taxes	136,003	160,783	45,578	305,521
Income tax provision	(274)	(262)	(181)	(413)
Net income	135,729	160,521	45,397	305,108
Less: Net income attributable to noncontrolling interests	(631)	(505)	(193)	(676)
Net income attributable to CFC	$ 135,098	$ 160,016	$ 45,204	$ 304,432