Equity - Schedule of components of equity (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021	May 31, 2020
Components of equity
Prior year-end cumulative derivative forward value gains (losses)	$ 92,363	$ (461,162)
Current-year derivative forward value gains	252,267	557,867	$ 621,946
Current year-end cumulative derivative forward value gains	342,624	92,363
Retained equity	2,553,716	2,112,315
Accumulated other comprehensive income	8,343	2,258
Total CFC equity	2,562,059	2,114,573
Noncontrolling interests	27,190	27,396
Total equity	2,589,249	2,141,969	1,399,879	$ 648,822
Membership Fees and Educational Fund
Components of equity
Total members' equity	3,534	3,387
Total equity	3,534	3,387	3,125	3,193
Membership fees
Components of equity
Total members' equity	969	970
Educational fund
Components of equity
Total members' equity	2,565	2,417
Patronage Capital Allocated
Components of equity
Total members' equity	1,006,115	954,988
Total equity	1,006,115	954,988	923,970	894,066
Members’ capital reserve
Components of equity
Total members' equity	1,202,152	1,062,286
Total equity	1,202,152	1,062,286	909,749	807,320
Other unallocated net loss
Components of equity
Total members' equity	(709)	(709)
Unallocated Net Income (Loss)
Components of equity
Total equity	341,915	91,654	$ (461,871)	$ (1,076,548)
CFC
Components of equity
Current-year derivative forward value gains	$ (250,261)	$ (553,525)