Bank segment - Reconciliation of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Condensed Income Statements, Captions [Line Items]
Revenues	$ 897,360	$ 895,685	$ 1,794,518	$ 1,823,922
Less / Add back: Retirement defined benefits credit—other than service costs	(1,281)	(1,153)	(2,563)	(2,305)
Total expenses	2,616,335	802,706	3,437,074	1,637,425
Operating income - bank	(1,718,975)	92,979	(1,642,556)	186,497
Loss before income taxes	(1,742,280)	69,367	(1,688,011)	139,671
American Savings Bank (ASB)
Condensed Income Statements, Captions [Line Items]
Interest and dividend income	86,178	81,741	174,113	161,220
Noninterest income	15,765	15,639	32,974	30,017
Less: Gain on sale of real estate	0	495	0	495
Revenues	101,943	96,885	207,087	190,742
Total interest expense	24,494	18,513	50,080	33,071
Provision for credit losses	(1,910)	43	(4,069)	1,218
Noninterest expense	136,465	53,769	192,369	108,186
Less / Add back: Retirement defined benefits credit—other than service costs	(280)	(187)	(561)	(374)
Total expenses	159,329	72,017	238,941	142,354
Operating income - bank	(57,386)	24,868	(31,854)	48,388
Loss before income taxes	$ (57,106)	$ 25,055	$ (31,293)	$ 48,762