Fair Value Measurement - Additional Information (Details)	Feb. 28, 2022 USD ($) borrower	May 31, 2021 USD ($) borrower	Feb. 28, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 30,815,241,000	$ 31,118,667,000
Total financial liabilities	29,096,276,000	29,418,975,000
Total loans outstanding	$ 29,508,363,000	$ 28,415,107,000	$ 28,315,671,000
Number of borrowers | borrower	885	892
Loans, fair value	$ 29,935,210,000	$ 29,967,692,000
Nonperforming financial instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans outstanding	$ 207,254,000	$ 237,497,000
Number of borrowers | borrower	2	4
Nonperforming financial instruments | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans outstanding	$ 0
RTFC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans outstanding	457,740,000	$ 420,383,000
RTFC | Nonperforming financial instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans outstanding	0	$ 9,185,000
Number of borrowers | borrower		2
RTFC | Nonperforming financial instruments | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans outstanding		$ 9,000,000
Number of borrowers | borrower		2
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	29,935,210,000	$ 29,967,692,000
Total financial liabilities	10,175,583,000	10,589,164,000
Loans, fair value	29,935,210,000	29,967,692,000
Level 3 | Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0		0
Total financial liabilities	$ 0		$ 0
Level 3 | RTFC | Nonperforming financial instruments | Fair value, nonrecurring | Collateral-dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value		$ 6,000,000