Leases - Finance lease ROU assets (Details) $ in Thousands	May 31, 2020 USD ($)
Property, Plant and Equipment [Line Items]
Weighted average remaining lease term (in years)	11 years 1 month 6 days
Weighted average discount rate	2.90%
Premises and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment - ROU assets	$ 500,830