Bank segment - Other borrowings (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Offsetting Liabilities [Line Items]
Gross amount  of recognized  liabilities	$ 284,000,000	$ 88,000,000
Gross amount  offset in the  Balance Sheets	0	0
Net amount of liabilities presented in the Balance Sheets	284,000,000	88,000,000
American Savings Bank (ASB)
Offsetting Liabilities [Line Items]
Advances from the FHLB	125,000,000	0
Net amount of liabilities presented in the Balance Sheets	284,000,000	88,300,000
Commercial account holders
Offsetting Liabilities [Line Items]
Net amount of liabilities presented in the Balance Sheets	284,000,000	88,000,000
Financial instruments	285,000,000	161,000,000
Cash collateral pledged	$ 0	$ 0