Bank segment - Income statement data (unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Noninterest expense
Income before income taxes	$ 59,626	$ 70,911	$ 111,208	$ 122,037
Income taxes	20,492	26,310	37,408	44,611
Net income	39,134	44,601	73,800	77,426
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	52,317	49,690	103,059	98,127
Interest and dividends on investment securities	6,763	4,443	13,743	9,460
Total interest and dividend income	59,080	54,133	116,802	107,587
Interest expense
Interest on deposit liabilities	2,311	1,691	4,414	3,283
Interest on other borrowings	824	1,467	1,640	2,952
Total interest expense	3,135	3,158	6,054	6,235
Net interest income	55,945	50,975	110,748	101,352
Provision for loan losses	2,834	4,753	6,741	9,519
Net interest income after provision for loan losses	53,111	46,222	104,007	91,833
Noninterest income
Fees from other financial services	5,810	5,701	11,420	11,200
Fee income on deposit liabilities	5,565	5,262	10,993	10,418
Fee income on other financial products	1,971	2,207	3,837	4,412
Bank-owned life insurance	1,925	1,006	2,908	2,004
Mortgage banking income	587	1,554	1,376	2,749
Gains on sale of investment securities, net	0	598	0	598
Other income, net	391	288	849	621
Total noninterest income	16,249	16,616	31,383	32,002
Noninterest expense
Compensation and employee benefits	24,742	21,919	47,979	44,353
Occupancy	4,185	4,115	8,339	8,253
Data processing	3,207	3,277	6,487	6,449
Services	2,766	2,755	5,126	5,666
Equipment	1,771	1,771	3,519	3,434
Office supplies, printing and postage	1,527	1,583	3,062	2,948
Marketing	839	899	1,356	1,760
FDIC insurance	822	913	1,550	1,797
Other expense	4,705	5,382	9,016	9,357
Total noninterest expense	44,564	42,614	86,434	84,017
Income before income taxes	24,796	20,224	48,956	39,818
Income taxes	8,063	6,939	16,410	13,860
Net income	$ 16,733	$ 13,285	$ 32,546	$ 25,958