Bank segment - Income statement data (unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Noninterest expense
Income before income taxes	$ 51,582	$ 51,126
Income taxes	16,916	18,301
Net income for common stock	34,193	32,352
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	50,742	48,437
Interest and dividends on investment securities	6,980	5,017
Total interest and dividend income	57,722	53,454
Interest expense
Interest on deposit liabilities	2,103	1,592
Interest on other borrowings	816	1,485
Total interest expense	2,919	3,077
Net interest income	54,803	50,377
Provision for loan losses	3,907	4,766
Net interest income after provision for loan losses	50,896	45,611
Noninterest income
Fees from other financial services	5,610	5,499
Fee income on deposit liabilities	5,428	5,156
Fee income on other financial products	1,866	2,205
Bank-owned life insurance	983	998
Mortgage banking income	789	1,195
Other income, net	458	333
Total noninterest income	15,134	15,386
Noninterest expense
Compensation and employee benefits	23,237	22,434
Occupancy	4,154	4,138
Data processing	3,280	3,172
Services	2,360	2,911
Equipment	1,748	1,663
Office supplies, printing and postage	1,535	1,365
Marketing	517	861
FDIC insurance	728	884
Other expense	4,311	3,975
Total noninterest expense	41,870	41,403
Income before income taxes	24,160	19,594
Income taxes	8,347	6,921
Net income for common stock	$ 15,813	$ 12,673