Bank segment - Narrative (Details) - USD ($)	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Allowance for credit losses
Securities sold under agreements to repurchase	$ 103,000,000		$ 90,000,000
Federal funds purchased	0		0
Proceeds from sale of available-for-sale investment securities	197,354,000	$ 0
Gross realized gains on available-for-sale securities	1,000,000.0	0
Gross realized losses on available-for-sale securities	500,000	0
American Savings Bank (ASB)
Allowance for credit losses
Securities sold under agreements to repurchase	102,700,000		89,700,000
Advances from the Federal Home Loan Bank	$ 0		$ 0
Minimum benchmark percentage of loan to appraisal ratio which mortgage insurance is required	80.00%
Minimum benchmark percentage of loan to appraisal ratio on non-owner occupied residential property	75.00%
Home equity line of credit
Allowance for credit losses
Conversion of debt	$ 6,200,000	1,800,000
Commercial
Allowance for credit losses
Conversion of debt	500,000	2,000,000.0
Consumer
Allowance for credit losses
Conversion of debt	$ 700,000	$ 1,000,000.0

Financing Receivable, Conversion Of Debt

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- Definition

Minimum Benchmark Percentage Of Loan To Appraisal Ratio On Non-Owner Occupied Residential Property

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No definition available.

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Represents the minimum benchmark percentage of loan to appraisal ratio which mortgage insurance is required as per the policy of the reporting entity.

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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