Bank segment - Income statement data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Noninterest expense
Income before income taxes	$ 53,276	$ 51,582
Income taxes	12,556	16,916
Net income	40,720	34,666
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	52,800	50,742
Interest and dividends on investment securities	9,202	6,980
Total interest and dividend income	62,002	57,722
Interest expense
Interest on deposit liabilities	2,957	2,103
Interest on other borrowings	496	816
Total interest expense	3,453	2,919
Net interest income	58,549	54,803
Provision for loan losses	3,541	3,907
Net interest income after provision for loan losses	55,008	50,896
Noninterest income
Fees from other financial services	4,654	5,610
Fee income on deposit liabilities	5,189	5,428
Fee income on other financial products	1,654	1,866
Bank-owned life insurance	871	983
Mortgage banking income	613	789
Other income, net	436	458
Total noninterest income	13,417	15,134
Noninterest expense
Compensation and employee benefits	24,440	23,042
Occupancy	4,280	4,154
Data processing	3,464	3,280
Services	3,047	2,360
Equipment	1,728	1,748
Office supplies, printing and postage	1,507	1,535
Marketing	645	517
FDIC insurance	713	728
Other expense	4,101	4,506
Total noninterest expense	43,925	41,870
Income before income taxes	24,500	24,160
Income taxes	5,540	8,347
Net income	$ 18,960	$ 15,813