Variable Interest Entities - Consolidated Assets and Liabilities of VIEs included in CFCs Condensed Consolidated Financial Statements (Details) - USD ($) $ in Thousands	Aug. 31, 2022	May 31, 2022	Aug. 31, 2021
Variable Interest Entity [Line Items]
Other assets	$ 27,504	$ 23,885
Total assets	32,082,294	31,251,382	$ 30,091,747
Total liabilities	29,835,359	29,109,413
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Loans outstanding	1,197,504	1,178,479
Other assets	9,725	9,672
Total assets	1,207,229	1,188,151
Total liabilities	$ 21,616	$ 22,958