Significant group concentrations of credit risk (Details)	12 Months Ended
Dec. 31, 2021
Major customers
Percentage of workforce covered by collective bargaining arrangement	50.00%
Percentage of benchmark loan to appraisal ratio in excess of which mortgage insurance is required	80.00%
American Savings Bank (ASB)
Major customers
Percentage of benchmark loan to appraisal ratio in excess of which mortgage insurance is required	80.00%

Percentage of entity's employees covered by collective-bargaining arrangement (CBA) to all participants in multiemployer pension plan determined to be individually insignificant.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration