Bank segment - Income statement data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Noninterest income
Noninterest income	$ 577,390	$ 575,465
Noninterest expense
Income before income taxes	58,039	53,276
Income taxes	11,878	12,556
Net income	46,161	40,720
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	57,860	52,800
Interest and dividends on investment securities	10,628	9,202
Total interest and dividend income	68,488	62,002
Interest expense
Interest on deposit liabilities	4,252	2,957
Interest on other borrowings	528	496
Total interest expense	4,780	3,453
Net interest income	63,708	58,549
Provision for loan losses	6,870	3,541
Net interest income after provision for loan losses	56,838	55,008
Noninterest income
Total noninterest income	14,564	13,417
Noninterest expense
Compensation and employee benefits	25,512	24,440
Occupancy	4,670	4,280
Data processing	3,738	3,464
Services	2,426	3,047
Equipment	2,064	1,728
Office supplies, printing and postage	1,360	1,507
Marketing	990	645
FDIC insurance	626	713
Other expense	3,854	4,101
Total noninterest expense	45,240	43,925
Income before income taxes	26,162	24,500
Income taxes	5,323	5,540
Net income	20,839	18,960
American Savings Bank (ASB) | Financial Services
Noninterest income
Noninterest income	4,562	4,654
American Savings Bank (ASB) | Deposit Liabilities
Noninterest income
Noninterest income	5,078	5,189
American Savings Bank (ASB) | Other Financial Products
Noninterest income
Noninterest income	1,593	1,654
American Savings Bank (ASB) | Bank-Owned Life Insurance
Noninterest income
Noninterest income	2,259	871
American Savings Bank (ASB) | Mortgage Banking
Noninterest income
Noninterest income	614	613
American Savings Bank (ASB) | Other income, net
Noninterest income
Noninterest income	$ 458	$ 436