Bank segment - Income statement data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Noninterest expense
Income before income taxes	$ 80,660	$ 75,543	$ 189,380	$ 212,595
Income taxes	29,516	27,264	70,406	76,302
Net income	51,144	48,279	118,974	136,293
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	46,413	45,532	137,646	133,065
Interest and dividends on investment securities	4,213	2,773	10,570	8,758
Total interest and dividend income	50,626	48,305	148,216	141,823
Interest expense
Interest on deposit liabilities	1,355	1,312	3,881	3,774
Interest on other borrowings	1,515	1,438	4,468	4,263
Total interest expense	2,870	2,750	8,349	8,037
Net interest income	47,756	45,555	139,867	133,786
Provision for loan losses	2,997	1,550	5,436	3,566
Net interest income after provision for loan losses	44,759	44,005	134,431	130,220
Noninterest income
Fees from other financial services	5,639	5,642	16,544	15,987
Fee income on deposit liabilities	5,883	5,109	16,622	14,175
Fee income on other financial products	2,096	1,971	6,088	6,325
Bank-owned life insurance	1,021	1,000	3,062	2,945
Mortgage banking income	1,437	875	5,327	1,749
Gains on sale of investment securities	0	0	0	2,847
Other income, net	2,389	634	3,363	1,920
Total noninterest income	18,465	15,231	51,006	45,948
Noninterest expense
Compensation and employee benefits	22,728	19,892	66,813	60,050
Occupancy	4,128	4,517	12,250	12,959
Data processing	3,032	2,684	9,101	8,715
Services	2,556	2,580	7,730	7,708
Equipment	1,608	1,672	4,999	4,926
Office supplies, printing and postage	1,511	1,415	4,297	4,487
Marketing	934	948	2,619	2,690
FDIC insurance	809	840	2,393	2,441
Other expense	5,116	4,182	14,076	11,198
Total noninterest expense	42,422	38,730	124,278	115,174
Income before income taxes	20,802	20,506	61,159	60,994
Income taxes	7,351	7,253	21,382	21,806
Net income	$ 13,451	$ 13,253	$ 39,777	$ 39,188