Bank segment - Reconciliation of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Condensed Income Statements, Captions [Line Items]
Revenues	$ 938,383	$ 901,873	$ 2,732,901	$ 2,725,795
Less / Add back: Retirement defined benefits credit—other than service costs	(1,106)	(1,256)	(3,669)	(3,561)
Total expenses	1,064,931	826,762	4,502,005	2,464,187
Operating income - bank	(126,548)	75,111	(1,769,104)	261,608
Income (loss) before income taxes	(149,234)	49,110	(1,837,245)	188,781
American Savings Bank (ASB)
Condensed Income Statements, Captions [Line Items]
Interest and dividend income	87,655	85,636	261,768	246,856
Noninterest income	17,489	15,338	50,463	45,355
Less: Gain on sale of real estate	0	0	0	495
Revenues	105,144	100,974	312,231	291,716
Total interest expense	25,421	23,044	75,501	56,115
Provision for credit losses	248	8,835	(3,821)	10,053
Noninterest expense	56,046	56,346	248,415	164,532
Less / Add back: Retirement defined benefits credit—other than service costs	(257)	(190)	(818)	(564)
Total expenses	81,972	88,415	320,913	230,769
Operating income - bank	23,172	12,559	(8,682)	60,947
Income (loss) before income taxes	$ 23,429	$ 12,749	$ (7,864)	$ 61,511